|At a Glance|
|Product||Belkin Gigabit Powerline HD Starter Kit (F5D4076)|
|Summary||HomePlug AV powerline adapter with proprietary throughput enhancements and Gigabit Ethernet LAN port|
|Pros||• 120 Mbps single-stream, 300 Mbps multi-stream maximum throughput
• HomePlug AV certified and interoperable
• Not sensitive to impulse line noise (dimmers, chargers)
|Cons||• Throughput drops very quickly with distance
• AFCI breakers really kill throughput
•Sensitive to broadband line noise (motors)
Belkin recently caused a stir in the powerline networking world with its announcement of a "Gigabit" powerline networking adapter capable of "ultrafast, high-quality transmission of multiple video streams, reducing online gaming latency and quickly transferring large data files". My immunity to marketing hyperbole would normally have caused me to pass on reviewing it, but two things caught my eye.
First, the adapter had a Gigabit Ethernet port, instead of the 10/100 port found even on "200 Mbps" HomePlug AV and UPA adapters. But, what really got my attention was that Belkin had tapped Gigle Semiconductor and not Intellon for the product's chipset. A little Googling led me to this whitepaper, which provided enough information to pique my interest and ask Belkin to send the product on over.
How It Works
Gigle uses the diagram in Figure 1 to illustrate how its solution improves upon HomePlug AV's throughput vs. "coverage" characteristics.
Figure 1: Gigle Throughput vs. "Coverage" Comparison
Figure 2, taken from an Intelllon whitepaper, shows that HomePlug AV uses frequencies from 1.8 MHz to around 30 MHz.
Figure 2: HomePlug AV Frequency Use
Gigle takes HomePlug AV and enhances it with two secret sauces. Mediaxtream basically uses higher frequency carriers that HomePlug AV doesn't use. This allows Gigle to achieve higher maximum throughput. But it also has some downsides, as we'll see when we look at performance test results.
The second sauce, xtendnet, uses mesh / AdHoc techniques to improve the throughput vs. "coverage" characteristics of an installation. Gigle doesn't provide specifics in the whitepaper. But the explanation I received in a call with Gigle and Belkin was that when an adapter is added to the network, the master node decides whether thoughput can be improved by forming a new network path through the added adapter.
Since the additional adapter will need to receive and then retransmit the packets, there is an automatic throughput hit of at least 50%, similar to what you get when using WDS-based wireless repeating. But if the paths to and from the new adapter are shorter, there will likely be higher bandwidth to start with. So there can be a net speed gain, even when the retransmission overhead is factored in.
I wasn't able to open the adapters without risking breaking their plastic shell. So I don't have any internal product shots. It's clear, however, that the adapters use Gigle's GCL541 1Gbps home networking IC for mediaxtream and HomePlugAV chip.
Setup And Administration
Belkin told me that the Gigabit Powerline HD Starter Kit (GPHD) is aimed more at non-technical folks who are putting together digital media setups vs. networking-savvy users. So they are not providing an installation / monitoring application with the product.
The only way you know what's going on is to use the lights on each adapter's front panel. Figure 3 provides a summary of what the LEDs mean. Note that the right-most light that has a Lock icon is the "Power" LED.
Figure 3: LED decoder
Like all HomePlug adapters, the Belkin adapters' data streams are secured with 128 bit AES encryption and the adapters come set with a default key. So installation consists of plugging the adapter into a wall outlet and running a cable from the adapter's 10/100/1000 Ethernet port to the device being networked.
The adapter auto-negotiates the Ethernet link speed and will connect to another adapter within seconds of it being plugged in. If you want to change the security code, you use the push-button on the top of each adapter.