The Next Generation Of Wi-Fi and Smartphones: Qualcomm 820 and Mu-MIMO

  • One of the interesting things in the next generation of Qualcomm’s Snapdragon platform, the 820 (due out in phones next year), comes with something called Mu-MIMO built in.  This is, in theory, is similar to the jump between megabit and gigabit wired networks and the first products in market to use this technology ae actually routers from Linksys.  To get a sense of the speed and performance of MU-MIMO I rigged 4 of these routers around my home office where I had been using more conventional SU-MIMO technology (all current generation) to see what the future will hold.  

    This is the result. 

    SU-MIMO vs. MU-MIMO

    We’ve had a lot of improvement to Wi-Fi over the years and performance has improved through the use of better radios, multiple antennas, and improved processing.  Arguably the best of the current generation of routers using SU (or Single User) MIMO (multi input multi output) is the Linksys AC1900 Reuter.  Its earlier generations are almost famous for reliability and range and this latest version is currently my primary router and I remain a fan.  

    But SU-MIMO only serves one device at a time switching quickly between each one.   But as you’ve likely seen when you at a conference, when you have a ton of people on the router or access point your data rate makes old analog modems seem fast.  You can get pretty decent speeds if you have a MIMO enabled device and there are just a few folks but as more people get on the network speed degrades sharply. 

    MU-MIMO is designed to service multiple devices at the same time, on paper this means you can have more devices at near full speed and you are more likely to be able to approach wired network speeds.  One of the firs routers to use MU-MIMO is the Linksys AC2600.  If the AC1900 is the last best of the old generation the AC2600 is the first of the new.  

    Now the issue is that to get the benefit of MU-MIMO you not only need a MU-MIMO router or access point but a MU-MIMO device as well.  Right now we are waiting for the first set of MU-MIMO PC Wi-Fi cards and the 820 chipset won’t be out in phones until next year. 

    So Qualcomm sent me 3 additional AC2600 routers and 3 MU-MIMO test phones and I spent a few days putting together a solution.

    The Test

    So what I did was is I used the routers like I would typically use switches.  I placed the first one in wired bridge mode and the others in wireless bridge mode.  Then I laid out a wireless network much like I would a wired network.  I had PCs spread throughout my home office and, unfortunately, I didn’t place the Ethernet jacks in the most ideal places so most Since I’d been using traditional wireless extenders I had a way to check the performance before and after and also check loading.

    My baseline was the machine I’m writing this from which is hardwired.   Before placing the PCs on the new routers I was seeing a 50% to 90% degradation of performance.  While the wired machine continued to outperform the wireless machines doubled and sometimes tripled performance when going from their shared SU-MIMO network to a nearly dedicated MU-MIMO alternative.  I did notice that you had to give the connected MU-MIMO routers priority or made sure the wired machines didn’t have priority (I’d initially set my wired office machine up as having network priority) otherwise they dropped in performance a lot if you were testing all of them at once.   But once the new wireless network had priority everything seemed to work impressively fast. 

    In effect I was able to get performance much closer to a wired network by linking the MU-MIMO routers together and using them as I’d typically use wired switches. 

    If nothing else this is a relatively inexpensive (and non-invasive) way to wire a home or small office where you don’t want or can’t open up the walls and clearly don’t want to run Ethernet wires all over the place. 

    Wrapping Up:

    If you want something that approaches wired gigabit network speeds but wirelessly the highest performance route is to set up a bunch of the new MU-MIMO routers and use them like you would switches.  Once this technology rolls out widely your new cell phones and new tablets will see similar benefits but remember the technology has to be at both ends so that means both the routers and your phone have to have it.  In the end this solves a problem for me as I wasn’t looking forward to pulling more cable under or through the house in order to get better bandwidth.