Maximum Wireless Throughput
We use the Ixia Veriwave that can emulate up to 4x4 ac devices to test maximum throughput. 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 AC1900 class products. Keep in mind we use 40 MHz bandwidth in 2.4 GHz for this test. Also note that the Veriwave does not support 160 MHz channels. We'll be testing that next.
This was the first time I tested a product using Marvell's 88W8964 radio SoC and have to say it was a difficult test. The initial results were so low I had to check with Linksys, who shared their Veriwave settings, which I ended up using. Still, the results below show the WRT3200ACM did not stack up well for this test.
Maximum Wireless Throughput comparison - 2.4 GHz
The WRT3200ACM ended up at the bottom of the group for three of the four benchmarks. Only 5 GHz uplink put the Linksys at the top of the heap.
Maximum Wireless Throughput comparison - 5 GHz
160 MHz Performance
I said at the top that the only device you can buy that supports contiguous 160 MHz bandwidth in 5 GHz is another WRT3200ACM. So that is what Linksys sent to test 160 MHz mode performance.
Two WRT3200ACM's were set up in open air about 8 feet apart, one acting as a router and the other set to wireless bridge mode. Channel 52 was set on the router and the bridge was connected to it. Test runs were made with 80 MHz bandwidth mode set, then with 160 MHz mode, with both router and bridge power cycled between. Note Channel 52 in 160 MHz mode uses all channels from 36 to 64, which includes DFS channels.
I connected the two wireless testbed computers at each end of the link, both of which are Intel Core i5 class machines. IxChariot test runs were done with the two computers connected via Gigabit Ethernet to establish the baseline references shown below. I used IxChariot's High Performance Throughput script with no changes and TCP/IP for all tests.
160 MHz test - Ethernet reference
Downlink runs with 80 MHz and 160 MHz modes set are compared below and show no significant difference between 80 and 160 MHz bandwidth. Uplink results were a bit higher, but essentially the same..
80 and 160 MHz mode comparison - downlink
I shared these results with Linksys, who suggested using four connections in the test. This yielded the results below, showing a 30% improvement using 160 MHz bandwidth mode.
80 and 160 MHz mode comparison - downlink - 4 connections
Uplink with four connections yielded a slightly better 37% throughput gain.
80 and 160 MHz mode comparison - downlink - 4 connections
I also ran Windows drag-and-drops of a 1 GB Windows backup file. Using snapshots at a similar point in each transfer, I saw downlink throughput increase from 82 to 99 MB/s (+21%) and uplink go from 80 to 105 MB/s (+31%). So 160 MHz mode can provide a nice throughput boost, if you don't mind eating up a lot of channels.
DFS obviously works, since I was able to run tests using 160 MHz mode. But I learned a few things about Linksys' current implementation and future plans that I'd like to share. I once again give credit to Linksys for answering my questions directly with no spin involved.
Linksys is currently not using the 5 GHz monitor radio. They instead use the 60 second Channel Availability Check (CAC) required by the FCC when radar is detected. This check drops all clients when radar is detected and maintains radio silence while further radar activity is monitored. In addition, when radar is detected on a channel, that channel won't be available again for 30 minutes, again due to FCC regulations.
There are only two contiguous 160 MHz channels currently available, 36 - 64 and 100 - 128. Channels 132 and up are greyed out in the channel selector when 160 MHz mode is enabled. This is due to a 5 MHz gap between channel 144 and 149, which doesn't allow a contiguous 160 MHz channel to be formed. So if you are dropped from the lower channel and have to move to the high (or vice versa) and radar is again detected within the 30 minute window, no clients will be allowed to connect to the 5 GHz band. Of course, if you are using 80 MHz bandwidth, you have more options when it comes to using DFS channels.
Linksys said it is working with Marvell on implementing DFS scanning in the dedicated monitor radio and plans to issue a firmware update once the function is working and FCC certified. However, Linksys has not commited to a timeframe for this.
If you want more details on DFS, including the channel plan, see How To Buy a Wireless Router - 2017 Edition.
The WRT3200ACM is the first router I've had on the test bench that is based on Marvell MU-MIMO. I had hoped it would just connect up and run with the Veriwave test set, but that was not to be. I'll continue to work with Linksys and Veriwave to resolve the problem and update this review (or publish results in another MU-MIMO round-up) if I get things working.
So Linksys wins bragging rights for getting to market with the first contiguous 160 MHz router. But as I've pointed out many times in this review, this isn't a particularly useful innovation unless you buy two WRT3200ACMs and use one as a bridge.
In the end, the WRT3200ACM is an expensive AC1900 router at $250, with wireless performance generally comparable to other AC1900 class routers. Its main competitive weakness is that it didn't produce downlink throughput as high as other products with strongest signals, which caused it to rank lower.
Wired routing throughput will be sufficient for the majority of users, with only those with true Gigabit service perhaps running into the throughput limits we saw in our testing. Its main strength, which it shares with its other Marvell-powered WRT brethren, is its superior storage sharing throughput.
The WRT3200ACM may have "the fastest 5 GHz band of any router", but it's not one that any mobile device is going to be able to take advantage of for years to come. Even die-hard future-proofers may want to take a long think before jumping on this band-wagon.