Powerline

I had long ago returned the Zyxel PLA-400, so turned to my closet to see what 200 Mbps powerline products lurked there. I found the Linksys PLK200 PowerLine AV Ethernet Adapter Kit, which I had never gotten around to reviewing. I also had the Netgear HDXB101 Powerline HD Network Kit, which was in a similar boat.

As is all too common, the desires of marketing people win out over not confusing potential customers. So it's not easy to tell which product supports which powerline technology. (The Linksys product uses HomePlug AV, while the Netgear uses DS2's 200 Mbps technology.)

I initially just plugged one of the PLE200 adapters from the PLK200 kit into a power outlet in my lab and the other into an outlet behind my TV and other media gear in my living room and expected flawless streaming. But when I saw the trailer clip quickly lose sync, then grind to a halt, I did the testing that I should have done in the first place.

Figure 3 tells the disappointing tale. The top trace was taken with two PLE200 adapters plugged into outlets in my lab. From previous testing, I knew that light dimmers could knock down powerline networking throughput. So at 20 seconds into the run, I flipped on a light plugged into a dimmer, plugged into a third outlet in the same room, then turned it off at the 40 second mark. You can see a 10-20% drop in throughput from the noise generated by the dimmer.

Figure 3: Linksys PLK200 throughput tests

The bottom trace is a run taken with one adapter plugged into a lab outlet and the other into a living room outlet. You can see a slow climb in throughput as the adaptive bandwidth algorithms in the PLE200's firmware try to find the right combination of frequency bands to use. But when I turned on my Panasonic plasma shortly before the 40 second mark, throughput took a dive down to an unusable 10 Mbps as soon as the screen lit up. Even though no light dimmers were around, it looks like the Linksys adapters didn't like the line noise coming out of the Panasonic set.

I then tried a quick same-room test on the Netgear powerline adapter set. But despite upgrading to the latest firmware, I was never able to achieve anything higher than around 3 Mbps of throughput. Since I know that DS2's 200 Mbps technology can do much better than that, I assumed the Netgear adapters were broken and set them aside.

Tags: 802.11n, HD, powerline, Streaming,

Related Articles: