Understanding where 802.11ad WiGig fits into the gigabit Wi-Fi picture

The wireless world is evolving rapidly in response to the explosion of intelligent devices, applications and data, and the IEEE 802.11ad standard, commonly known as WiGig, is poised to help.

WiGig is a step change from the 802.11 evolution we have witnessed over the last 10 years, adding a new frequency band, 60 GHz, to existing products: 802.11n operates in the 2.4-GHz and 5-GHz bands, while newer 802.11ac products operate in the 5-GHz band.

By enabling the emergence of tri-band products — such as 802.11n/ac + 802.11ad — WiGig opens the door to exciting applications and makes it more possible for all intelligent devices to be connected through a high speed Wi-Fi network.

But, we get ahead of ourselves. First, let’s see what WiGig is all about.

* Speed. The WiGig spec is defined to support speeds up to 7Gbps, but this is really just a start. By using some of the basic techniques we see today in .11n and .11ac, up to 100Gbps is achievable within the next few years. How?

•  While .11ac can go up to 8×8 MIMO, 256 QAM modulation and channel bond four 40 MHz channels, .11ad is able to achieve the same speeds with one spatial stream, 64 QAM modulation and a single channel.

•  Using all of the techniques that 802.11 has used in the last decade to achieve higher performance in the legacy bands (channel bonding and MIMO and higher modulation), the Wi-Fi industry can easily achieve much faster speeds.

• Using an industry analogy – 60 GHz technology today is in the “.11b phase” of the technology evolution. We are just at the beginning of an exciting technical road map progression that will take WiGig to new heights using proven techniques, as well as new ones, yet to be discovered.

* High capacity. 16-32 antenna element arrays generate real spatial separation and make high capacity wireless deployments a reality.

• Approximately the same area of a single 2.4 GHz antenna module can contain 32 or more 60GHz antennas.  

• Beamforming with such a large antenna array allows for highly directive communication, allowing for multiple devices working side by side in the same room with minimal effect on devices around them.

• Interference-free transmissions allow for capacity to be additive. In most omni-directional radio technologies, the overall bandwidth is divided by the number of users, which is dilutive rather than additive.

* Most power efficient Wi-Fi technology yet. Running multiple gigabits per second of real throughput at only hundreds of milliwatts total system power is achievable with 802.11ad, making it far and away the most power efficient technology in the Wi-Fi portfolio.

• Power splits differently between 60GHz radios and traditional Wi-Fi products in legacy bands.  

• Receiver data processing is biggest energy consumer, rather than transmit power amplifiers.

• A full system, generating a 20+ dBm effective isotropic radiated power (EIRP) and sustaining a 4Gbps link can be built at 0.5 W (1/2 Watt), aligning well for phone/tablet integration.

* Great free space rate/range. Path loss offset by antenna gain and wide channel enables high speed, even in low signal-to-noise ratio (SNR) situations. 2Gbps at 100 feet is “easy.”

• One of the biggest misconceptions of 60GHz is that it is short range.

• 60 GHz does not have a range problem. In fact, in free space line-of-sight, 60GHz has the best rate/range profile of any Wi-Fi technology.

• But 60GHz does have a blockage problem. It doesn’t go through most walls or through people. Rather, it reflects. Therefore, while 60GHz has the best rate/range, it often must use this range to find a reflective path in-room to get to its target.

* Coverage. When discussing WiGig performance, we need some new terminology. Standard rate/range graphs have become familiar but do not apply here.

• One can be 100 feet away and get 2Gbps or, due to blockage and required reflections, one can be 10 feet away but only get 1Gbps.

• For WiGig, we talk about coverage. In a typical room, what percent of the time can I achieve a specific rate – for example, in a conference room, 65% of the locations can achieve 4Gbps, 80% can achieve 2Gbps, and 95% can achieve 1Gbps.

* Very low latency. Around ~10 microseconds (us) round trip is real, comparable to wire latencies.

• WiGig was designed from the ground up to be extremely low latency – ~10 us round trip – comparable to wired-equivalent latencies. This is important, because now the latencies are close enough that you can trick the system that it is running over a wire. And if the system thinks there is a wire, you can reuse all of the software that has been developed for that environment.

For example, WiGig Wireless Bus Extension (WBE) is able to run the PCIe bus over the air, and therefore, seamlessly reuse the last decade’s worth of host controllers and device drivers that have already been developed.   

In summary, WiGig offers unrivaled raw speed, interference resistance, good range, high capacity networking, multi-gigabit real throughput in a handheld power envelope, and near-wire equivalent latency. Given these benefits, WiGig is well-suited for a broad range of applications, from tri-band networking (2.4/5/60 GHz) to wireless storage and edge caching to wireless docking. Products integrating WiGig are currently available in the market, including multiple Ultrabook SKUs and a wireless docking station, and more products are on the horizon.

Mark Grodzinsky is Vice President at Wilocity