This is my first test of three-stream N products using a "real" three-stream N client. My previous three-stream tests used the three-stream N capable Intel Wi-Fi Link 5300 AGN mini-PCIe card, but with a third antenna jury-rigged onto an Acer Aspire 1810T notebook running Win 7 Home Premium (Figure 8).
Figure 8: Acer Aspire 1810T with third antenna - bottom view
Since this isn't an vendor-designed solution, I limited my tests to same room (Location A) testing. But with the TEW-687GA, I could run a full set of six-location tests using both 20 MHz and 40 MHz bandwidth modes without having TRENDnet call foul for inappropriate test methodology.
I asked TRENDnet to send a new TEW-691GR 450 Mbps Wireless N Gigabit Router, because I had given the review sample away in an SNB contest. It came with 220.127.116.11 firmware, which was newer than the 18.104.22.168 firmware used in my two-stream testing. The TEW-687GA had 22.214.171.124 firmware installed—the only version available.
Figure 9 shows a composite IxChariot aggregate plot for all 2.4 GHz band downlink tests using 20 MHz channel width. The throughput numbers are higher than I've seen with practically all two-stream N routers running in 40 MHz bandwidth mode!
Figure 9: TRENDnet TEW-691GR router with TRENDnet TEW-687A client - 20 MHz mode
Note that throughput is much smoother than I saw using my jury-rigged three-antenna setup, even at the lower-signal locations.
The highest link rate I saw during 20 MHz mode testing was 195 Mbps in Location A. Since this information isn't available in the 687A's admin interface, I had to get it from the TEW-691GR's Wireless Station List display. Highest link rate seen in Auto 20/40 MHz mode was 405 Mbps, not 450.
Note also the throughput step-up during the Location A run. I saw similar effects throughout my testing, particularly at my "dead-zone" locations E and F and using Auto 20/40 mode.
Switching to Auto 20/40 MHz bandwidth mode, kicked performance up quite a bit. Figure 10 shows Location A average downlink speed of 134 Mbps for the one minute test with a peak speed of 146 Mbps during the test.
Figure 10: TRENDnet TEW-691GR router with TRENDnet TEW-687A client - Auto 20/40 MHz mode
The downside of using Auto 20/40 mode is less reliable and lower speed operation with weak signal levels. I originally failed to get tests to run in Locations E and F in Auto 20/40 mode at all. But when I later came back to try the tests one more time, I was able to get the results shown.
I recorded the highest bandwidth of 173 Mbps shown in Figure 11 running four simultaneous downlink streams in Auto 20/40 mode. But even running simultaneous up and downlink traffic with only one stream each direction in Auto 20/40 mode yielded 168 Mbps of total bandwidth!
Figure 11: TRENDnet TEW-691GR router with TRENDnet TEW-687A client - Auto 20/40 MHz mode - 4 streams
Here are links to other IxChariot wireless test plots if you'd like to explore further:
- 2.4 GHz / 20 MHz uplink
- 2.4 GHz / 20 MHz up and downlink
- 2.4 GHz / 40 MHz downlink
- 2.4 GHz / 40 MHz uplink
- 2.4 GHz / 40 MHz up and downlink
Since this is my first real three-stream test, there really aren't any comparable products in the Wireless Charts database. I've entered the TEW-687GA's results as a new TEW-691GR *3 Stream Test* entry, but flagged the results with a red bar color so you know that you're looking at different test conditions.
Figure 12: TEW-691GR / TEW-687GA Wireless Performance Table
A look at the table brings home the point that three-stream N doesn't really help under low borderline signal conditions and is more likely to hurt, especially when using 40 MHz bandwidth mode. But that's a lesson we learned long ago with two-stream N, anyway.
I have to say that I'm surprised and maybe even have to eat a bit of crow here based on these results. I'm so accustomed to vendors over-hyping wireless products that I've learned to look carefully at every new-and-improved performance claim. And in most cases, they fall short of hyperventilated marketing claims.
But it seems that, at least for a direct matchup of a Ralink RT3883F based router and client bridge, that three stream N really can provide significantly higher throughput than you can get from any two-stream N product combination on the market. And whoda thunk that TRENDnet would be the folks to get this significant leap in 802.11n performance to market first?
My testing has not tested the reasons I heard at CES for the introduction of three-stream-in-5 GHz-only routers like the Linksys E4200, i.e. that three-stream N is hard to maintain in the crowded 2.4 GHz band. My test environment is pristine with no other active networks in range and no 2.4 or 5 GHz stray RF either (DECT 6.0 phones are the only way to go, folks).
But with no other traffic in range, the link rates that I recorded during testing showed that three-stream rates were being used all the way out through Location D and fell back to two-stream rates only in "dead-zone" locations E and F.
This certainly bodes well for high-def streamers yearning for more wireless bandwidth. The TEW-691GR and TEW-687GA are your best shot yet at 100 Mbps+ wireless bandwidth in locations other than the same room. So let's hear from you brave pioneers who are willing to take the plunge! It will be interesting to see if the warnings are true and three-stream rates will be harder to get when the spectrum gets crowded.