WiGig – threat or opportunity for small cells

Wi-Gig logoWiGig (pronounced Y-Gig) is an organisation promoting the new 802.11ad wireless standard, one of many in the 802.11 series better known to most people as Wi-Fi. WiGig is similar to Wi-Fi except it operates at astounding speeds of between 1and 7 Gbit/s over short range – typically 10m or so. As part of the 802.11 family of standards it is also backward compatible with the mainstream Wi-Fi bands at 2.4GHz and 5GHz, but is uses the much higher 60GHz band where the highest data rates are possible.

Many countries have assigned 7GHz or more of spectrum in the 60GHz band, and this is either unlicensed (like Wi-Fi at 2.4GHz today) or lightly licenced. For example, in the UK and US, the 57 to 64GHz band is licence exempt. The 64 to 66GHz band is lightly licenced in the UK, meaning that users should notify the regulator where and when they use the frequency but there is no fee for doing so. It simply allows awareness of existing use prior to installation and resolves potentially unusual cases of interference.

Transmissions at this frequency are inhibited due by oxygen (16 dB/km) and by any moisture in the atmosphere. The signal at these frequencies won't go through walls and probably won't even go through your body, so is really of greatest use for high speed transmission when in very close proximity. Think of WiGig as a wireless replacement for USB3.0 or Thunderbolt cables, allowing HD video to be streamed and enabling very fast data backups and/or sync between devices.

Short range is an advantage after all

While the very short range of 60GHz spectrum might at first appear to be a disadvantage, the benefit is that the same frequencies can be reused close by. Unlike Wi-Fi, you shouldn't expect to pick up your neighbour's WiGig signals and can use it simultaneously in multiple rooms in your own house for different applications.

For the technically minded, where the line of sight link budget falls off by 34dB within 1 metre for 2.4GHz Wi-Fi, the same transmission at 60GHz WiGig is attenuated at 68dB – simply due to the higher frequency.

Therefore, the technology is great for short burst, high throughput transmissions. You could download a full (30 Gbyte) HD video in less than 60 seconds. This makes it ideal for synchronising devices or downloading purchased content very quickly at a point of sale. For example, at a major sports or entertainment event, you could download the "event program" (more likely to be a full HD app with all the bells and whistles than a paper leaflet) when buying your ticket at the door.

Consumer products

In October 2012, Dell announced the first WiGig equipped laptop, the Latitude 6430U. Imagine being able to connect to a powerpoint projector wirelessly when visiting to make a presentation, or docking with your second display, backup device etc. wirelessly at full speed.

Over the next couple of years it will be one of the main options for quick and easy data delivery without the need for a physical wired connection. Since it won't go through walls and has very short range, it's more useful for close proximity transfers and won't replace or directly supersede Wi-Fi or cellular directly. Many consumer electronic devices will be multi-mode Wi-Fi and WiGig capable.

An example might be purchasing an HD movie to play on your mobile device (smartphone or tablet). While you could buy this and stream it as you watch over 3G or 4G, you could also have the option to download it from a nearby terminal so that it's on your device for viewing offline at any time. This may be particularly attractive for retail stores who can deliver content at the point of sale.

Consequences for the mobile wireless industry

The consequence of the wireless and consumer industries are two-fold:

  1. WiGig will offer another alternative data delivery mechanism to complement the cellular and Wi-Fi networks of today, helping to relieve the pressure of data traffic in the highest usage urban areas.
  2. WiGig technology can also be used in the short range wireless backhaul for urban metrocells. Widespread consumer adoption should drive chipset costs down dramatically, which also makes 60GHz wireless backhaul more attractive.

But wouldn't consumers using Wi-Gig interfere with metrocell backhaul if they operate at the same frequency?

That's not the case, says Mark Barrett, CMO of Blu Wireless Technology, who cites the substantial difference in performance between the two applications. "Metrocell backhaul would use high gain antennas with greater than 30dB of gain and less than 5 degree beam width, so that the probability of interference is already low. They will be scaled down to run at hundreds of Megabits over several hundred metres, where consumers will passing Gigabits over one or two meters.

"Interference from these short range transmissions will be insignificant when more than a few metres away.

"In the UK, the lightly licenced 64-66 band may be used for backhaul and other commercial use, leaving the licence exempt 57-64 band for mass consumer use.

"Furthermore, mass market consumer takeup of WiGig will drive the cost of the technology down substantially. This will enable very cost competitive WiGig backhaul. Of course, it will still require an antenna, specialist RF front end circuitry and additional management software which will add to the cost.

"A further enhancement being worked on is looking at how to avoid the need for manual alignment of the antenna. This is similar to the alignment required to install a broadcast satellite TV dish, manually adjusting the physical tilt and azimuth of the antenna. A scheme which automatically aligns the beam without manual intervention would simplify installation. It would also allow later realignment, even to a different hub, by remote control." (Readers will have spotted that another radio link will be required to remotely control it during this process, but that might be made through a nearby macrocell or even another nearby metrocell).

Summary

WiGig will be another useful part of the toolkit for ubiquitous data connectivity. Principally designed for very high speed/close proximity transmissions, mass market takeup for use with consumer electronics should drive the unit costs down substantially.

The effects on mobile networks will be two-fold:

  1. Offloading very high data transfers, which can be deferred to happen quickly when very close to a WiGig point, typically at home. This will relieve high traffic load from the cellular network.
  2. Enabling lower cost short range wireless backhaul for metrocells, with rates of hundreds of Megabits at distances of hundreds of metres. This is very much line-of-sight transmission, but ideal for many urban city centre applications.

The huge amount of unlicensed or lightly licensed spectrum at 60GHz – with more than 7GHz bandwidth available – at virtually zero cost makes this an attractive option for the future.

--

My thanks to Mark Barrett, CMO of Blu Wireless Technology, for his help in explaining this new technology. His company is a Silicon Intellectual Property design company, working with several major wireless semiconductor suppliers who are actively developing WiGig chipsets with planned commercial availability of Q4 2013.

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