Introduction
Updated 8/12/2010: Added link to six location wireless test article
TRENDnet decided to make a liar of me and ship the first three-stream (450 Mbps maximum link rate) N router to become available. So as soon as it came in, I put it on the test bench to see what, if any, improvement three stream N offers over two-stream. But first, let’s take a quick look at the hardware.
The Hardware
The 691GR looks like many of TRENDnet’s other wireless routers, coming packaged in a glossy-black plastic case. The only ventilation holes are on the side of the case and a vertical stand doesn’t come with the router. So, as you might expect, it gets a tad warm, even when sitting idle.
The rear view in Figure 1 shows the three non-upgradeable antennas, single WAN and four switched LAN ports and Power and WLAN switches. All Ethernet ports are 10/100/1000 and there’s also a WPS pushbotton on the left side panel.
Figure 1: TRENDnet TEW-691GR rear view
Figure 2 shows the FCC ID photo (FCC ID XU8TEW691GR) for the board. It uses a Ralink RT3883F 802.11n 2.4/5GHz 3T3R 450/450Mbps Single Chip AP/Router SoC. This is Ralink’s second pass at a three-stream N chip, replacing the RT2883 used in first generation routers that never shipped.
Figure 2: TRENDnet TEW-691GR board
You can also see an Atheros device, but it’s an AR8316 Gigabit switch, which handles the single WAN and four LAN 10/100/1000 Ethernet ports. A Winbond W9751G6JB provides 64 MB of RAM and a Macronix 29LV640 adds 8 MB of flash. The three small devices surrounded by RF shields are SST12LP15A‘s, which are 2.4 GHz amplifiers.
Although the three antennas are connected to the board via mini connectors (Hirose U.FL, I think), there are no rear-panel connectors. So there is no easy antenna upgrade path.
Note while the Ralink chip is a dual-band device, there is no option in the admin GUI to switch to 5 GHz. And even if there were, the aforementioned 2.4 GHz amplifiers would prohibit its use anyway.
As a final construction note, I opened up my sample and found that the FCC photo is accurate in that neither the Ralink nor Atheros devices have heatsinks.
Wireless Features
I’ll do a more complete runthrough of the 691GR’s features when I post the full review. But I thought you’d like to see the wireless controls that TRENDnet provides in the meantime. Figure 3 shows the Basic wireless settings. Note the multiple SSIDs, which would let you set up guest networks. Each SSID can have its own wireless security settings. But there are no settings for controlling access to the wired or other wireless LANs.
Figure 3: TRENDnet TEW-691GR Basic Wireless controls
WDS is also supported, which the online help says is implemented in repeating mode, without the option to switch to bridging only mode.
The full-sized image shows the HT Physical Mode controls, which include Channel Bandwidth, Guard Interval, MCS and Extension Channel. Of these controls, the only ones you’ll likely need to play with are the Channel Bandwidth (to kick it up to full 450 Mbps mode) and Extension Channel (if you want to try to be more neighbor friendly when using Channel 6 and Auto 20/40 MHz mode).
The MCS setting lets you force the maximum link rate used if you think that will help you get a better performing connection (it most likely won’t). Values supported are MCS 0-15 and 32 and, of course, the default Auto mode. The MCS index table shown in Figure 4 is a bit hard to follow. But note the second column (Number of spatial streams).
Figure 4: MCS index table (courtesy Agilent Technologies)
MCS 16-23 contain values for the three spatial streams required to achieve the maximum 450 Mbps link rate (MCS 23). But the MCS control doesn’t include these values. Note that you’ll get a maximum link rate of 217 Mbps in the default 20 MHz channel bandwidth mode.
The router’s Help file contains a reference to an Operating Mode control that TRENDnet wisely removed from the GUI. The settings of Mixed Mode and Green Field would likely have confused people and just given them one more control that was more likely to screw them up vs. helping improve performance.
Advanced wireless settings are shown in Figure 5. The most useful control here is the Transmit power, which has Full (default), Half and Low settings.
Figure 5: TRENDnet TEW-691GR Advanced Wireless settings
Routing Performance
Routing performance for the 691GR using our standard test method is summarized in Table 1 and Figure 6 shows the composite IxChariot plot for the three routing speed tests.
| Test Description | Throughput – (Mbps) |
|---|---|
| WAN – LAN |
262
|
| LAN – WAN |
314
|
| Total Simultaneous |
286
|
| Maximum Simultaneous Connections | 14,983 |
| Firmware Version |
1.0.0.0
|
Table 1: Routing throughput
It’s easier to see that unidirectional routing speed was much more steady in both directions than the bidirectional test by looking at their individual test plots (WAN to LAN plot, LAN to WAN plot).
Figure 6: TRENDnet TEW-691GR routing throughput
The Maximum Simultaneous Session test topped out at 14,983 sessions. Since this isn’t near a binary multiple boundary, I didn’t round the result.
Use the Router Charts to see how the 691GR stacks up against other routers.
Wireless Performance – Two Stream
I thought I was all set to start testing three-stream products, since my standard N test client is an Intel WiFi Link 5300. This is the only adapter available (besides Intel’s newer 6300-series adapters) to support three-stream N. But I ran smack into the same obstacle that everyone else will—the lack of a third antenna in my test notebook.
Like, I think, every other notebook, the Dell Mini 12 I use for wireless testing has only two antennas, which are connected to the terminals labeled 1 and 2 on the 5300 card. So when I first fired up the router, which properly defaults to 20 MHz channel bandwidth mode, I got the same 130 Mbps link rate obtained with dual-stream routers. And when I set the router to Auto 20/40MHz channel bandwidth mode, from its default 20 MHz mode, I got only a 300 Mbps link rate.
Since I’ve heard claims that using a three-stream router will improve the performance of two-stream clients, I ran uplink, downlink and simultanous up / down tests with the router and client in the same room, 10 feet apart. (This is my test Location A).
For this first round of tests, I used our standard open air test method to test wireless performance and our standard wireless test client, an Intel Wi-Fi Link 5300 AGN mini-PCIe card in a Dell Mini 12 running WinXP Home SP3 and version 13.1.1.1 of the Intel drivers. I left all client-side defaults in place.
Figure 7 shows a composite IxChariot plot of the three tests. Throughput is not steady at all in any of the runs. And though speed averaged over the one minute test period is higher than the typical two-stream router I test, it’s not higher than the highest wireless throughput two-stream routers I’ve tested, like the D-Link DIR-685 and NETGEAR WNDR3700.
Figure 7: TRENDnet TEW-691GR wireless performance – two antenna client, 20 MHz B/W mode
If you want to compare for yourself, head over to the Wireless Charts, pick a few routers at the top of the charts and click the Performance Table button. Make sure you compare only the results for Location A, 20 MHz bandwidth mode.
Switching to Auto 20/40 MHz bandwidth mode, kicked performance up quite a bit. Figure 8 shows top speeds close to 100 Mbps for the uplink and bidirectional tests.
Figure 8: TRENDnet TEW-691GR wireless performance – two antenna client, 40 MHz B/W mode
Again, this performance isn’t unheard of in two-stream routers, but it’s more atypical of what I see. Note, however that this speed comes with very high throughput variation. Check the individual downlink plot to see what I mean.
Wireless Performance – Three Stream
To perform tests using all three streams, I had to get another antenna attached to the Intel 5300 card. Since getting to the wireless card in the Dell Mini 12 requires significant disassembly, I turned to my Acer Aspire 1810T. Getting to the Acer’s wireless card is easy, requiring only the simple removal of a panel on the bottom of the machine.
As I surveyed my stock of past-reviewed routers, I remembered the D-Link DIR-655 that had died after only a month of service. After some minor surgery, I had transplanted its connectorized antenna and internal pigtail cable to the Aspire.
Figure 9: Acer Aspire 1810T with third antenna – bottom view
The pictures in Figures 9 and 10 show the result ain’t pretty, but it got the job done.
Figure 10: Acer Aspire 1810T with third antenna – top view
With this third antenna attached to the Intel 5300 card’s terminal 3, I now got a 217 Mbps link rate with the router set to 20 MHz channel bandwidth mode and 450 Mbps with Auto 20/40 MHz mode.
I reran the tests with the router set to 20 MHz channel bandwidth and got the unimpressive results shown in Figure 11.
Figure 11: TRENDnet TEW-691GR wireless performance – three antenna client, 20 MHz B/W mode
Downlink speed is again the slowest—exactly the opposite of what potential HD video streamers want! But the extrememely high throughput variation would kill any hope of trouble-free streaming anyway.
By the way, I kept an eye on the link rate during testing and found it constantly bounced around, spending very little time at 450 Mbps. And remember, this was with router and client in the same room, only 10 feet apart!
Figure 12: TRENDnet TEW-691GR wireless performance – three antenna client, 40 MHz B/W mode
Figure 12 shows the results when I switched the router to Auto 20/40 MHz channel bandwidth mode. While it was nice to see results close to 100 Mbps, once again, I’ve seen similar speeds from the DIR-685 and WNDR3700.
Closing Thoughts
I’ll be running a full set of six location tests with both two and three antenna clients in the next few weeks. But, to tell the truth, I’m not really in a hurry to do them, because the key "reveal" has already been done.
I hope as much as you do that this first test of three stream N technology isn’t the final word on what this much-awaited technology can produce. But, at least for now, it shows that three-stream N technology isn’t yet capable of delivering better performance than you can already get with better-performing dual-stream gear.