Draft 11n Wireless
For my 5 GHz draft 11n wireless test, I pulled out the Netgear WNHDE111 [reviewed]. It fit the bill for what I needed and, from my previous testing, I knew that this product had very high throughput. The downside is that 5 GHz draft 11n doesn't have great range, especially when used in the 40 MHz bandwidth mode. But my previous testing showed plenty of throughput in the spot where I was using it.
Figure 4 compares the WNHDE111 and another draft 11n wireless bridge product, the D-Link DAP-1522 [reviewed]. Both products have similar range, i.e. don't reach my farther three test locations. But the WNHDE111 has over twice the throughput at Location C (which is the same as Location 3).
Figure 4: 5 GHz downlink throughput comparison
The tested throughput indicated that I should have had trouble-free streaming, and that was almost the case. I ran through my collection of test clips and only occasionially saw the audio and video temporarily lose sync.
Figure 5 shows the reason for the occasional problems and points out the problem with even 5 GHz draft 11n.
Figure 5: WNHDE111 throughput - 3 minutes
Even though average throughput is around 3X what's needed to play most of my test clips, you can see some flailing around between 30 and 50 seconds into the run. This certainly isn't from any interference sources, since my environment is clear of even 2.4 GHz neighbors. And I even recently dumped my 5.8 GHz cordless phones (which also used the 2.4 GHz band) in favor of WLAN interference-free DECT 6.0 phones.
Instead, the throughput drops are probably due to ranging or other algorithms that are part of the WNHDE111's design. I should note that I ran other extended tests and saw similar glitches, although they didn't last as long or drop as low. But as I found in Video Streaming Need To Know: Part 1- Encoding, Bit Rates and Errors, it takes packet loss as little as only 0.05% to introduce visible problems in standard definition video streams.
I was surprised that draft 11n wireless did as well as it did and that powerline did so poorly. But the Netgear solution won't solve everyone's wireless HD streaming problems. It just happened that the product's range and my requirements matched nicely to provide high enough throughput (if you ignore the occasional glitches). In your home, they might not.
The bottom line is that the best solution for trouble-free HD streaming is still good ol' Ethernet. There's just no alternative yet that can beat it for delivering reliable, glitch-free bandwidth no matter where you need it.