Performance With Interference
Now things start to get interesting. We wanted to examine the role of interference in 11ac throughput. Obviously, there are many ways to go about this, from industrial-grade RF emitters to the kitchen microwave oven. For the sake of simplicity and reproduction, we decided to use one of our spare routers as an interfering source. Specifically, we set the Nighthawk up as a client adapter on the same channel frequency, plugged it into a client notebook and set it on the table about two feet from the router under test directly in the line of sight path between test router and client adapter on the other side of the room. When we test the Nighthawk, we use the Asus as our interfering client. We then had the interfering router pull in a continuous Netflix stream from the home network. Given the multi-path nature of MIMO, we clearly couldn’t disrupt all paths into the test router, but this approach seemed like it should provide at least some competition for our test subjects and apply some stress on their ability to cope with competing ambient traffic.
Again, we’ll run the baseline results next to the current test results for comparison. In three out of four cases, performance declined in the face of 5GHz interference. Strangely, the exception was our R6300, which picked up a roughly 15% performance gain on server-to-client transferring. Everybody else seems to have suffered from the RF competition. Amped and the Nighthawk in particular appear to have been hit hardest.
In our PassMark test, every router loses performance. Recall that our baseline showed us hitting that 410-ish Mb/s ceiling, especially in UDP throughput. With interference, only the Nighthawk can keep scratching that UDP maximum. Every other score suffers, including the Nighthawk’s TCP speed. This time around, the Amped router seems particularly wounded. Combined with the 2GB test, this has us starting to wonder if Amped’s 2x2 antenna design leaves it more susceptible to 5GHz environmental issues.
We see another anomaly here with the Nighthawk battling through interference from the R63000 to pull in even faster numbers, albeit not stunningly accelerated. The R6300 sees some elevation in its performance floor, but the reduction in its ceiling yields a slower overall average. The Amped and Asus units get hammered particularly hard by 5GHz interference.
As one might expect from UDP, in which there’s no mandate to resend failed packets, we see very little difference in our baseline and interference results. In fact, here you can see the Nighthawk’s 5GHz IxChariot graph results, with the interference results shown on the right.
Very similar, right? The interfered pattern shows a bit less spiking up toward 140 Mb/s, but otherwise the graph seems little affected.
Let’s see if these results carry over into our 2.4GHz interference comparisons.
Right off the bat, we would answer no. TCP traffic gets mauled like a bear victim with a broken leg. Why, you think, there’s no way that Asus could really take almost 1550 seconds to complete the client-to-server test. That’s nearly half an hour! Yes, Marsha, it’s true. We ran it twice. The Nighthawk won this race simply by being the only router to have one result that didn’t double or triple from our baseline.
The bad news is only confirmed by PassMark. All routers take it in the kidneys. Our beloved AC66U from the prior round-up sees its UDP traffic in particular crushed. The Nighthawk again wins through sheer force of staying upright throughout the interference storm.
Again, be careful of the x-axis scale; it could be misleading. Amped may have won our baseline test for 2.4GHz TCP in IxChariot, but in the face of interference it loses roughly two-thirds of its throughput. Asus likewise wears a boat anchor into the dark depths. Damage for the R6300 isn’t as relatively bad, but, then again, it had less to lose when starting in last place. By only sacrificing about 20%, the Nighthawk looks downright awesome.
Check out the instant replay. TCP or UDP, the impact of interference on the 2.4GHz band remains almost the same. Again, the Nighthawk withstands assault well, and the Asus serves as a warning for future generations. Just look at the Asus' comparison between baseline (left) and interfered here.
