When building networks in the ‘real world’ like city centers, stadiums, apartment buildings, and even office buildings, we frequently come across situations where many access points, installed independently or managed as one network, create overlapping coverage areas. When these access points choose to use the same channel, the performance of all users in such an area is reduced, as the Wi-Fi algorithm used to avoid collisions on the air is quite conservative.

One focus of the next Wi-Fi standard, 802.11ax is to improve the performance of ‘real-world’ networks. To this end, the new standard includes a feature enabling more simultaneous transmissions. This feature is known as ‘spatial reuse’ or ‘BSS coloring.’

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As we explore the new features appearing in 802.11ax, the list is unbalanced. Some would say there’s a pig in the python. One feature – OFDMA – seems much more significant than the others. First, a brief background, then a view of its implications.

A Quick Review of OFDMA

OFDMA (Orthogonal Frequency Division Multiple Access) is an extension of the OFDM (Orthogonal Frequency Division Multiplexing) architecture. OFDM takes an RF channel, such as the 20 MHz channel often used in Wi-Fi, and instead of using a single carrier-frequency modulated by AM, FM, or other means, sets out a number of sub-carriers. 802.11ac used 52 data-carrying sub-carriers in a 20 MHz RF channel, while 802.11ax has 234.

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Today we focus on when new 802.11ax access points and client devices will become available. The Wi-Fi industry has made these questions uniquely difficult to answer, but this blog explains what we expect to happen. If you have the patience, save these predictions for rereading toward the end of 2019!

The three important milestones along the path to commercial equipment are the IEEE 802.11ax standard, the Wi-Fi Alliance 11ax certification, and integrated circuit chips. These are a sequence in time, but with a lot of overlap.

The First Milestone: IEEE
The IEEE writes standards: very detailed definitions of the packet formats, fields, and functions that make the protocols work. IEEE 802.11ax is written as an amendment to the current 802.11 standards and eventually will be folded into the mainstream 802.11 document. Even as an amendment, however, it is 600 pages long. Getting every detail of such a standard correct requires scrutiny from many experts, and the IEEE process involves reviewing drafts and submitting comments and corrections, which then update new drafts, and are reviewed again.

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We normally think of Passpoint, the Wi-Fi Alliance certification, as a feature for Wi-Fi hotspots owned and operated by service providers. Passpoint enables comprehensive inter-carrier roaming, with discovery, authentication and accounting.

But, as with any good protocol, the possible applications greatly outstrip the scenarios originally considered. Enterprise access points already support Passpoint. And as implementation in phones moves forward, slowly but surely non-carriers are finding interesting new applications.

Passpoint’s big innovation is decoupling service advertising from the Service Set Identifier (SSID). An access point can advertise, in addition to its SSID, a number of service providers that provide roaming possibilities. When a device starts authentication, the access point relays to the respective service provider’s authentication server, then provides an internet connection.

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Machine learning is a modern wonder, but as with any new technology, opinions differ as to what the future holds. Some label it a fad, while others see limitless applications.

We are firmly in the optimistic camp. Machine learning, even as it continues to develop, is already widely understood, and open-source libraries and cloud computing engines make the technology accessible to every software engineer. Most important, machine learning solutions are finding their way into enterprise networks. We already see machine learning applied to problems such as network management, enterprise security and IoT.

+ Also on Network World: Microsoft wants to bring machine learning into the mainstream +

As various enterprise networking vendors and startups incorporate machine learning, they are adopting very similar architectures, reinforcing a change in the way we view the network.

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The allocation of radio spectrum is a fiercely contested matter. Government regulators—the FCC in the U.S., OFCOM in the U.K., and others—manage spectrum as a national resource. They seek to balance the needs of various groups, including cellular operators, government users, scientific and amateur radio groups. And, of course, they represent the public both directly and via their political masters.

Industries that depend on access to spectrum must work hard to ensure continuing access, and they must head off proposals for new services that might cause interference. As established users of the 2.4 GHz and 5 GHz bands, here are some of the areas where the Wi-Fi industry is active today, working with regulators.

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Many of us cordially detest virtual LANs (VLANs). They require complicated configuration, and consequently they are error-prone. They do not offer fully satisfactory solutions for the problems they are employed to solve, primarily limiting broadcast traffic and segregating devices and their traffic for security purposes. But as the least-worst alternative, they are a fact of life in many networks.

Recent developments in WLAN and data center networking offer opportunities to escape VLANs.

In the enterprise Wi-Fi world, it has long been important to reduce broadcast traffic over the air, and WLAN vendors have been developing techniques along these lines for years. An early feature allowed an access point to act as an ARP proxy for its client devices, answering on their behalf. The success of proxy-ARP functions engendered intervention in other broadcast/multicast protocols to reduce unnecessary traffic and improve performance.

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Even as we increase data rates and network capacity in Wi-Fi with 802.11ac, 11ad and then 11ax, it’s worth keeping an eye on other communication technologies that may become useful in the enterprise.

Visible light communication (VLC) is making progress in the background, and while it is barely out of the lab, it may take off in a few years. The startups working with enterprise VLC are adopting the term “LiFi” (although it has—today—no connection with Wi-Fi).

Like all new technologies, there are many possibilities—and the number of potential uses is impressive. Applications include vehicle-to-vehicle, underwater communications, streetlamps, aircraft cabins, and industrial uses where Wi-Fi cannot be used due to RF interference.

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We are used to external developments driving progress in enterprise networking. An obvious example is the modern smartphone, born in the consumer market but now the primary client for enterprise WLANs.

Another is the move towards white-box networking, an extraordinary change in the way enterprises build data centers that would not have happened but for the activities of the big consumer internet companies.

So, it is natural to look to other markets for technologies that may become important in the enterprise over the next few years. In wireless, Bluetooth is the one to watch.

Bluetooth Low Energy: wireless technology of choice

Bluetooth has enjoyed an extraordinary rise since re-inventing itself with BLE (Bluetooth Low Energy, also called Bluetooth Smart and Bluetooth 4.0) in 2010. Its main benefits are very low-cost chips and very low power, enabling inexpensive battery-powered devices that run for years.

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Somewhere there’s an alternate universe where service providers are so effective that they dominate the enterprise communications market.

In that world: What cannot be delivered remotely over fiber, wires or wireless—a pervasive, shared communications grid—is installed on site and managed remotely by service provider engineers. Small businesses and large enterprises requiring wired or wireless communications look to these large service providers because they deliver all required services at the lowest cost, with high reliability and national reach. At the end of the month, a single bill covers all services consumed.

+ Also on Network World: IoT-dedicated networks beginning to rollout +

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How far should a leader seek to change public opinion, to get out in front rather than follow? Lincoln famously said, “Public sentiment is everything,” but the quote concludes with, “He who moulds public sentiment… makes decisions possible.” It’s an enduring debate in the hinterland of academia where engineers seldom tread.

But standards can be like that. They often package basic, universal features with more decorative additions that offer transformational improvements but are of minority interest. There’s a risk that the burden of implementing these additional features will deter some vendors, and they may shun the standard altogether. If too many follow this course, the standard will fail in the market. 

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Two decades ago, the core was the place to be in campus networking. The networking battles of the 1990s concluded with the edge specialists humbled and assimilated by core product lines. Control the core, we declared, and the edge will fall into place.

But now the edge is fruitful, and the core is sterile—and for two reasons. First, the wireless interface adds mobility and complexity to the edge. Second, the new architectures of software-defined networking (SDN) and IoT are based on centralized models that take sensed information, manipulate a software representation of the network, then send control signals back to network nodes. Nodes are peers under the controller. Their importance is based on the quantity and quality of the information they can report, as well as the sophistication of the control they can apply.

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The recent launch of two residential Wi-Fi products—from eero and Luma—is very welcome. They highlight just how stale the traditional offerings had become. But their central technical improvement should be unnecessary.

The new devices apply the Nest treatment to Wi-Fi routers rather than thermostats. As with most brilliant ideas, one’s first reaction is why didn’t someone do this before, it’s so obvious?

+ Also on Network World: Riding the new Wi-Fi wave (part 1) +

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