Maximum Wireless Throughput
Since throughput vs. attenuation plots are now done with a 2x2 STA, we use the Ixia Veriwave that can emulate up to 4x4 ac devices. The results posted are an average of 10 one minute test runs. This benchmark is fully described in the Revision 9 test process description. We're again comparing the C3150 with the ASUS RT-AC88U.
2.4 GHz results show the two products with essentially identical maximum throughput, both uplink and downlink. The products are again essentially the same for 5 GHz downlink. The only significant difference is in 5 GHz uplink, where the AC88U's top throughput is about 90 Mbps higher than the C3150's.
Maximum Wireless Throughput comparison
It's interesting to note neither product would run the 5 GHz test at the maximum VHT MCS9 (1733 Mbps) rate. I had to drop the TP-LINK to MCS8 (1560 Mbps) and the ASUS to MCS7 (1300 Mbps). I'm not surprised by this. When I previously ran this test using a pair of the same router with one in bridge mode, I seldom would see them link at the maximum rate.
The Linksys EA9500 review provided our first look at "working" MU-MIMO on a Broadcom-based product and the results were not pretty. The Linksys was able to muster only 151 Mbps of total throughput gain using MU-MIMO vs. throughput using SU-MIMO (normal) clients. So I didn't expect much better from the Archer C3150.
The C3150 did even worse than the Linksys, showing no gain whatsoever from MU-MIMO operation. I ran the test multiple times with the same result.
The Veriwave system reports the number of MU frames used by each device, which is very helpful. The report with two MU devices connected showed each device using only 3% MU frames. When the number of MU devices increased to three, the MU frame percentage dropped to 0.002 and 0.003 for two of the devices, with the third using no MU frames at all. When the number of MU devices was increased beyond three, no MU frames were reported.
I shared these results with both TP-LINK and Veriwave for a sanity check before publishing this review . I have yet to see a Broadcom-based MU-MIMO product produce results anywhere near those from QCA-based products and wanted to know what their results showed. Unfortunately, I could not get data to confirm or refute my results from either source.
So at this point, I have to say that I can't confirm whether the Archer C3150 has working MU-MIMO. I'll update this review if I hear or can produce test results otherwise.
Regular SmallNetBuilder readers know I don't have high expectations for the practical benefit MU-MIMO will provide for most Wi-Fi users. The Archer C3150 does nothing to change my mind. When MU-MIMO works, it requires at least two devices, both with strong signals, to provide its benefit of higher total throughput. But most of us have yet to attach a single MU-MIMO device to our networks, let alone two. So buying a MU-MIMO router for the "benefit" of MU-MIMO or, worse yet, "future proofing", is an investment that may never pay off.
On the other hand, now that I'm testing with a 2x2 STA, our test results more accurately reflect what folks see from real-world devices. And it appears that 4x4 routers, no thanks to MU-MIMO, can push the throughput vs. attenuation (aka rate vs. range) curve above that of 3x3 AC1900 routers.
The plot below compares two AC1900 class routers—D-Link's DIR-879 and NETGEAR's R7000 original Nighthawk—with two 4x4 AC3100 / 3150 class routers—the Archer C3150 and ASUS RT-AC88U—tested with our standard 2x2 Intel AC client.
4x4 vs. 3x3 througput vs. attenuation
You can check all four plots and see results similar to the 5 GHz downlink plot above. These results suggest that upgrading to an 4x4 router might provide a benefit that has nothing to do with MU-MIMO, i.e. a throughput boost from the signal gain provided by more wireless streams. I hope to run another open-air study soon to see if these improvements occur outside the test chamber.
In the meantime, if you already have an AC2600 router, like the top-ranked NETGEAR R7800 or its #1 ranked predecessor, TP-LINK's Archer C2600, there is no reason to move to the TP-LINK Archer C3150 or any AC3100 / 3150 router, including the more expensive ASUS' RT-AC88U. Both are 4x4 routers that can provide the same rate vs. range improvement shown above. The AC3100's higher number is there to suck in Wi-Fi noobs who don't know better. The higher link rates require devices that support Broadcom's proprietary 1024-QAM modultation in a 4x4 radio, which basically means another Broadcom-based 4x4 router in bridge mode.