- C.J. Mathias
While many enterprises are knee-deep in 802.11n wireless migration, and some are even eyeing 802.11ac with its 1.3 Gbps of throughput, another higher throughput wireless standard is on the horizon – 802.11ad gigabit wireless.
The 802.11ad gigabit wireless standard offers an unprecedented 7 Gbps of throughput. While the technology has its challenges, it could supplement existing wireless networks, better enabling large-scale BYOD connectivity and high-speed video delivery.
802.11ad was originally developed by the Wireless Gigabit Alliance, which has since merged with the Wi-Fi Alliance, the organization responsible for developing every major Wi-Fi standard, including 802.11b, g, a, n and ac. Now the Wi-Fi Alliance is set to release an 802.11ad specification in early 2014, which is likely to bring the technology into the mainstream for both consumers and the enterprise.
802.11ad is super-fast, but there’s a catch
The 802.11ad standard is known for its 7 Gbps of throughput, but raw specifications tell only part of the story.
The standard operates in 60 GHz bands, differing from 802.11n, which works in both the 2.4 and 5 GHz bands, and 802.11ac, which runs in the 5 GHz band. Like 2.4 and 5 GHz, the 60 GHz bands are unlicensed in most parts of the world, but the frequency trumps the other bands, offering between seven and nine GHz of spectrum, as compared to 84 MHz at 2.4 GHz and about 1 GHz at 5 GHz.
Yet, the 60 GHz spectrum is also known as the “oxygen absorption band.” That means radio waves at those frequencies are actually degraded by the presence of oxygen in the air. For this reason, 60 GHz was considered only appropriate for point-to-point, outdoor applications using highly-directional antennas (e.g., wireless links between two networks) until recently. It could also be used in outer space for inter-satellite communications where oxygen is obviously not a problem, or for indoor short-range applications, such as linking device docks with wireless interconnects.
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As it turns out, though, the degradation caused by oxygen really isn’t all that bad and most regulators around the globe allow fairly high-power transmissions and antenna gains at 60 GHz, at least partially compensating for the behavior of the air. Higher power transmission enables more range even though the air at those frequencies absorbs some of that power. The concept is similar to speaking louder at noisy cocktail parties to get your message heard.
However, a bigger challenge for 60 GHz systems is going through walls. The extent of these problems is influenced by a number of factors, including the distance between endpoints, building construction (dense concrete walls will always be an issue), and the type of antennas applied.
Antennas play a critical role in all wireless network performance, but even more so in the case of 60 GHz, where the inherent directionality of the radio waves themselves can be challenging. Nonetheless, there’s a good deal of technology that can be thrown at the propagation problem to improve performance in all dimensions, including range, throughput, reliability and capacity. One of these technologies is complementary metal-oxide semiconductor chips, which are less expensive than other silicon chips and reduce concerns about range performance and reliability by better using spectrum.
Do we need 7 Gbps of throughput?
Considering that 802.11ac already offers such high throughput, do we really need 802.11ad? After all, what enterprise applications really require throughput on the order of 7 Gbps?
It’s generally wrong to think in terms of throughput alone because capacity is just as important. In this case, capacity refers to the ability of networks to meet the ever-growing traffic requirements of certain sets of super users. Technology based on the 802.11ad standard can supplement existing wireless networks, giving network managers the ability to offload heavy demands on 2.4 and 5 GHz. That’s where large-scale BYOD connectivity and high-speed video come in.
Will 802.11ad change the BYOD connectivity game?
The BYOD phenomenon is driving demand for enterprise network connectivity, much of which depends on wireless LAN capacity. Given the limited number of channels available to Wi-Fi systems today, access to more spectrum is more than enticing, especially for power users, such as universities that must serve tens of thousands of users that each bring multiple devices.
The basic proposition is that the faster any given user gets bits reliably on and off the air, the more capacity is left for everyone else—and 7 Gbps enables a lot of capacity.
What’s more, in the open-office environments typical today, the propagation of 60 GHz signals shouldn’t be an issue. In fact, the relatively limited range of 60 GHz enhances frequency reuse (using the same spectrum in multiple locations simultaneously without mutual interference). This might even augment overall wireless security because eavesdroppers outside a given installation will have a much more difficult time grabbing 60 GHz signals.
However, in the short term, 80211.ad can’t be used for BYOD because it’s not natively supported in most user devices. For now, 802.11ad could be used as a notebook tool with add-on adapters (although some laptops will have it built-in). As the technology moves into the mainstream, more supportive devices will emerge.
Using 802.11ad for high definition, streaming video
Streaming video consumes more bandwidth than almost any other application in the enterprise, so it could play a role in pushing 802.11ad uptake. As the use of video grows, network managers will need to offload this traffic from networks to leave room for more general traffic, and 802.11ad is an obvious choice because it provides so much capacity.
For most video, network managers plan on about 20 Mbps per video stream for reasonable frame rates, resolution and overall quality. But 60 GHz can be immediately useful in HDMI video links, which require about 3.3 Gbps for uncompressed transmission. While this is more of a residential application, eventually it will move into the enterprise and 802.11ad will become necessary.
To be sure, 802.11ad technology is nascent and many parts of the market won’t need it for a very long time. Yet consumption will increase, and in the meantime engineers will continue to tackle the technical challenges of this high-throughput gigabit wireless.
Craig J. Mathias is a principal with Farpoint Group, an advisory firm specializing in wireless networking and mobile computing. Founded in 1991, Farpoint Group works with technology developers, manufacturers, carriers and operators, enterprises and the financial community. Craig is an internationally recognized industry and technology analyst, consultant, conference speaker, author, columnist and blogger.
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