Brian's Brain

Back in late July, I shared my initial (and underwhelming) testing results on Belkin's Gigabit Powerline Adapters based on Gigle Semiconductor's GGL541 devices (PDF), which I also mentioned in my late August cover story.

Not only did the 'Gigabit' adapters not exhibit the higher-than-HomePlug AV speeds promised by Gigle's Mediaxtreme technology, they delivered slower bandwidth than conventional HomePlug AV adapter equivalents (NETGEAR's XAV101). Gigle immediately asked me to ship the adapters back to the company, and after a series of delays, I received them back last week with upgraded firmware that supposedly not only improves Mediaxtreme capabilities but also bonds the 2-to-28 MHz HomePlug AV and 50-to-300 MHz Mediaxtreme bands.

Unfortunately, at least in my particular setup, the firmware update seems to have resulted in a performance setback. Recall that I use powerline networking to connect both my home automation controller and two Xbox 360s (acting, among other things, as Media Center Extenders) to my router. The Media Center server, a Dell laptop running Windows Vista Ultimate, connects to the router either via powerline or 802.11n. As review, here are my late-July results for a powerline-only topology using the Belkin/Gigle 'Gigabit' adapters:

versus the same topology employing NETGEAR HomePlug AV devices:

The 'Acceptable for TV' threshold is 8 Mbps, while the 'HDTV' line is 22 Mbps; the transport protocol used by Media Center is UDP, along with RTP for multimedia streaming and RTSP for control functions.

Now let's look at how the Belkin adapters did with Gigle's latest firmware. First, here's the measured bandwidth in a five-adapter configuration (both Xbox 360s, only one of which was on at the time, plus the Universal Devices home automation controller, the router, and the Dell laptop):

Switch the Dell laptop connection from powerline to 802.11n, remove its corresponding adapter from the power grid, and here's the result:

Next, I swapped out the Belkin adapters for the NETGEAR HomePlug AV predecessors. Here's the five-adapter powerline-only topology:

And here's the 'hybrid' four-adapter configuration with the Dell laptop tethered to the router over 802.11n:

As you can see, the Gigle/Belkin adapters not only consistently under-perform their HomePlug AV counterparts in similar topology configurations, they run slower than they did the first time around in an identical configuration. Gigle will, after seeing this data, request the adapters back for yet another firmware turn. Will the third time be the charm? Stay tuned...