If all clients use the same standard, bandwidth sharing should be equal... theoretically. In the real world, differences in adapter design, host platform OS and architecture and RF environment result in somewhat less than ideal throughput sharing.
During the last round of experimentation, I ran a quick check using two NETGEAR A6200 AC1200 class USB adapters connected to a NETGEAR R7000 router and got the result shown in the IxChariot plot below.
Two AC1200 clients on AC1900 router
The host machines used had both different processors (Intel Core i5-4200 vs. Core i3-2310M) and OS (Win 8.1 64 bit vs. Win 7 Home Premium SP1 64 bit), but the same adapters. Two interesting observations from the experiment are:
- Bandwidth sharing was not equal
- Total bandwidth use did not exceed the 199 Mbps observed with a single AC867 client
The second observation is particularly interesting because the test router is AC1900 class and produced a peak downlink throughput of 409 Mbps with our AC1750 class standard client in the ideal conditions of our closed test chamber.
NETGEAR R7000 - 5 GHz downlink throughput profile
But inquiring minds also wanted to know what happens when different AC class clients are mixed. So let's take a look.
First, let's recap the products used. The test router for these experiments was again the NETGEAR R7000 "Nighthawk" [reviewed] loaded with V188.8.131.52_1.0.15 firmware. There was no particular reason for choosing this router other than I had it on hand.
I used three test clients with the router, representing AC1750, AC1200 and AC580 classes. These have maximum AC 5 GHz link rates of 1300, 867 and 433 Mbps, respectively. So they are identified in the plots as AC1300, AC867 and AC433.
- AC1300: Our standard AC test client composed of a Dell Optiplex 790 Small Form Factor (SFF) computer (Core i5-2400 @ 3.1 GHz / 4 GB RAM) running Win 7 Pro with an ASUS PCE-AC66 AC1750 PCIe adapter with Win 7 184.108.40.206 driver. The adapter uses a Broadcom BCM4360 chipset.
- AC867: Acer Aspire S7-392 running Win 8.1 64 bit with NETGEAR A6200 AC1200 class adapter [reviewed] with 220.127.116.11 utility and 18.104.22.168 driver. The adapter uses a Broadcom BCM43526 chipset. The Acer's internal Intel Wireless-N 7260 adapter was disabled.
- AC433: Lenovo X220i running Win 7 Home Premium SP1 64 bit with Linksys AE6000 AC580 class USB adapter with 22.214.171.124 driver. This adapter uses a Mediatek MT7610UN chipset.
The router and all three clients were set up in my test lab with all clients within 10 feet of the router. Tests were run with the router set to channel 153 using open-air testing and IxChariot's throughput.scr script with TCP/IP and test file sizes of 5,000,000 Bytes. No other networks were operating during the tests.
The Tests - Solo
As before, the three clients were run individually to establish their maximum throughput levels. The composite plot below shows the AC433 class Linksys adapter actually produced higher throughput than the AC867 class NETGEAR! The throughput jump 15 seconds into the AC1300 plot is an artifact of IxChariot's TCP/IP handling under high-throughput.
The AC1300 Mbps client produced 220 Mbps average throughput and 260 Mbps peak. This establishes the maximum downlink throughput available for this test setup. If the router can support all three clients at their maximums, it will need to provide over 530 Mbps of total bandwidth. It clearly can't do that. But will it produce the 409 Mbps peak we got in our chamber testing?
Composite plot of individual tests - downlink
For the sake of completeness, here's the composite plot of three individual uplink tests. This time, the AC867 class adapter did much better and the AC433, much worse. But average throughput for the AC1300 client was again around 250 Mbps.