Wireless Reviews

Wireless Performance - Overview

Out of the box, the Centria defaults to NETGEAR's version of 20 MHz mode ("Up to 195 Mbps") on the 2.4 GHz radio and Auto 20/40 ("Up to 450 Mbps") on 5 GHz. Both bands have Wi-Fi Protected Setup (WPS) enabled and prompted to enter the router's PIN on first association of the Win 7 test notebook. After entering the PIN, a WPA2/AES connection was quickly set up and used for all further testing.

I ran 40 MHz Coexistence and Fat channel intolerant tests and found that the Centria properly refrained from switching into 40 MHz bandwidth mode for both tests. When I reassociated the notebook during both tests, the client showed only 20 MHz mode link rates.

I used our Intel Centrino Ultimate-N 6300 in a Lenovo X220i notebook running Win 7 Home Premium SP1 (64 bit) standard test client for all three stream testing. Our other standard test client, an Intel Centrino Advanced-N 6200 in a Acer Aspire 1810T notebook running Win 7 Home Premium SP1 (64 bit) was used for two-stream tests. V1.0.0.32 firmware was loaded in both routers for all testing.

As is our standard practice, all tests were run using WPA2/AES encrypted connections with Channel 1 used for 2.4 GHz tests and Channel 36 for 5 GHz, using our standard wireless router test suite.

Each entry in the Benchmark Summary below shows the average of throughput measurements made in all test locations.

NETGEAR WNDR4700 Benchmark Summary

If you look closely at the table, you'll see that, in general, the CENTRIA has higher throughput running uplink vs. downlink, with a difference of about 2X in many cases. The good news is that the CENTRIA turns in some of the highest throughput we've seen in a three-stream N router. But for wireless HD streaming, you want that throughput in the downlink direction and the CENTRIA provides just the opposite.

Table 2 summarizes the highest wireless throughput measured out of all locations in the 20 MHz mode test runs. In most cases, highest throughput was measured in Location A. Note that the Dn/Up result is for simultaneous up and downlink tests in Location A.

Test Group	Max Dn (Mbps)	Max Up (Mbps)	Dn/Up (Mbps)
2.4 GHz, 2 stream, 20 MHz	63	94	93
2.4 GHz, 3 stream, 20 MHz	47	82	32
5 GHz, 2 stream, 20 MHz	65	92	97
5 GHz, 3 stream, 20 MHz	66	83	88

Table 2: Highest Throughput, 20 MHz mode

The table shows that 20 MHz mode three-stream performance in both bands tends to go in the opposite direction of what you would want, i.e. lower. You'll see the detail behind this in the sections that follow. But the overall pattern isn't what you want.

Table 3 summarizes highest 40 MHz mode throughput. The two-to-three stream trend here is in the correct direction and even shows some significant (~40%) gains.

Test Group	Max Dn (Mbps)	Max Up (Mbps)	Dn/Up (Mbps)
2.4 GHz, 2 stream, 40 MHz	68	133	100
2.4 GHz, 3 stream, 40 MHz	96	157	165
5 GHz, 2 stream, 40 MHz	65	126	110
5 GHz, 3 stream, 40 MHz	88	169	174

Table 3: Highest Throughput, 40 MHz mode

This provides some hope for high 5 GHz downlink throughput, but not so much for 2.4 GHz. Even if you force the CENTRIA to blast away in 40 MHz mode when it shouldn't, competition from busy neighboring networks won't be kind to your throughput stability.

Wireless Performance - 2.4 GHz 2 Stream

For performance comparison, I chose three other "N900" routers: ASUS RT-N66U, Cisco/Linksys E4200v2/EA4500 and NETGEAR WNDR4500. Let's start with the Performance Table for Two-stream 2.4 GHz.

As noted in the summary above, CENTRIA generally provides higher throughput running uplink vs. downlink. You'll see this pattern in all the tests. You'll also see it in the Performance Table linked above, where the CENTRIA wins the uplink comparisons handily in both 20 MHz and 40MHz modes.

Oddly, the CENTRIA's downlink throughput doesn't benefit from 40 MHz mode operation. It turned in virtually identical results in all locations except weakest-signal location F, where 40 MHz mode throughput was 4 Mbps vs. 18 Mbps in 20 MHz mode.

Highest throughput measured was 133 Mbps running uplink, 40 MHz mode in Location A. This was higher than the 100 Mbps simultaneous up/down test in the same mode.

The IxChariot plot summary below for 20 MHz mode downlink shows generally good throughput stability, but with some periods of link shifting evident in the Location D trace. As is our practice, I repeated the test a few times and got similar behavior each time.

IxChariot plot summary - 2.4 GHz, 20 MHz mode, downlink, 2 stream

You will also see that it takes up to 10 seconds for the CENTRIA and test client to negotiate the highest link rate in some of the other plots linked below. Most notably in the 20 MHz uplink run.

• 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