The wild, wireless world: Will new MU-MIMO technology triple wireless speeds?


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Greetings to all my fellow techies. For several years now, I’ve been studying and reviewing wireless technologies. Back in the day, I used to set up access points and receivers so I could run files wirelessly through an obstacle course, recording throughput rates over time and distance.As such, I’ve seen signal strength and range improve steadily over the years, up to the current 802.11n standard that offers real-world speeds of up to about 140Mbits per second when used with channel bonding and packet aggregation.

However, the biggest effect on wireless speeds has been the MIMO (Multiple Input and Multiple Output) technology that allows multiple signals to be processed at the same time. It’s why all 802.11n routers have three antennas, even if they are hidden inside the box. But MIMO has thus far had a fairly significant drawback.

Fast forward to last week. The scene is a tiny wireless carrier’s store, the kind that sells devices and plans for a single company’s wireless service. My wife was looking for a new tablet, and I was along for the ride. For some reason, the store didn’t have its own wireless connection, which I found pretty odd for a business that sold wireless devices. The salesperson said not to worry, because the nearby coffee shop had an open hub. However, when we tried to connect, the throughput rate was so terrible that not very much could be done in terms of taking the tablet for a spin. Obviously, we didn’t buy a tablet from that store.

However, I was a bit curious as to why we couldn’t connect wirelessly to the open hub, so I headed over to the coffee shop. Sure enough, it was packed with people enjoying iced chai teas and frothy cappuccinos while typing out text messages and updating their Facebook pages. There were more wireless devices inside that place than cups of coffee, and there was a lot of coffee. I immediately saw the problem.

Even though MIMO supports multiple channels with 802.11n, it’s still designed to work with individual users. That’s fine for most homes or private settings, and fine for coffee shops at off-hours. But it’s really bad when a lot of people are trying to use the signal. At the equivalent of rush hour for a wireless access point, the router will allot a tiny slice of time for each user before moving on to the next one. So Customer One gets so many milliseconds of individual time with the router before it moves on to Customer Two. If there are only two people, then the first person in line gets the signal back at that point and doesn’t even notice the difference. This round robin access plan works fine for a handful of people. But when you have 20 users trying to share, the delay becomes significant, even crippling.

If you add in less than optimal conditions, such as being too far away from the hub or having barriers in-between, then those precious milliseconds given to a user can be wasted. The router doesn’t consider how strong or weak a signal is when allotting time. It provides access to a device in the chain and moves on whether it’s being used effectively or not. So in the coffee shop example, people down at the wireless store being a 100 feet away with walls in-between have a minimal chance to use the signal.

Many agencies and businesses that try to provide wireless access to their employees face the same problems. How effective your wireless signal is at work might depend on where you cubical sits and how many users are trying to access the hub at the same time. Instead of a window seat, you might be better off vying for something closer to the hub.

Enter 802.11ac, a new standard that could triple wireless speeds at work or in any place where a signal is publicly shared. Promoted by Qualcomm, it allows for users in an MIMO environment to group up. Remember those three antennas on every access point? Instead of using all of them to direct multiple streams to single users in turn, it instead groups some users together. So in a sense, it allows users who have an 802.11ac chipset receiver in their notebooks to team up with others and share their turn with the router.

Technically, the router is still playing round robin with its users, but more devices are able to take a turn at the same time. Even if you don’t have the new chipset in your device, most smartphones likely won’t have it for a very long time — though many high-end laptops already do, you will still see a speed increase. Why? Because all those who have an 802.11ac receiver will be able to group up and take their turns together, meaning a shorter wait for the router to get back to you as an individual user.

The most interesting thing about 802.11ac is that it’s an innovation that works within today’s existing signal strength and technology. We’ve really gone almost as far as we can with raw wireless speeds. When they start to equal or rival wired networks, you can’t get much better.

So instead, Qualcomm and others are using the existing technology and enhancing it. Those who have tried to work wirelessly in a crowded office, not to mention an airport or a coffee shop, know that the crowded nature of the wireless world makes that task difficult. Hopefully, 802.11ac will ease that burden a bit. It will also allow agencies and businesses that have given up on wireless technology for being too unreliable an opportunity to take a second look, and hopefully get better results overall.

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Commentary, Guest Columns, MU-MIMO, Qualcomm, Technocrat
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