Ethernet cable (either CAT5e or CAT6) is the gold standard of home-networking technology. If you can string cable from your router to everywhere you need Internet access, do it. You'll get out-of-this-world speed and impeccable reliability.
That's easier said than done, of course, which is why there are alternatives. Wi-Fi is the easiest to deploy, but its range can be limited and you might have areas that wireless signals can't reach at all. That leaves you with two other courses of action, both of which piggyback on your home's existing wiring: Powerline network adapters (which use electrical wiring) and MoCA network adapters (Multimedia over Coax, which use the same cable as your TV). So which is the better alternative?
To answer that question, I compared the performance of one of the fastest powerline network adapter kits, ZyXel's PLA5405KIT (based on the HomePlug AV2 MIMO standard) to one of the few MoCA adapter kits on the market: Actiontec's Coax Network Adapter Kit (model number ECB2500CK01).
I have a network homerun in my equipment closet, meaning all of my home's telephone, Ethernet, and coax cables terminate there. This is where my DSL modem, Wi-Fi router, Ethernet switches, six-way coax splitter, and uninterruptible power supply are all located, so this where I conducted my tests. I installed the second adapters in my home theater.
First up: Powerline adapters
I plugged one of ZyXel's PLA5405 adapters directly into the wall at my homerun and connected it to my router using a CAT5e cable. I plugged a second PLA5405 into a receptacle in my home theater and connected it to my home-theater PC for measuring TCP throughput.
As with all the products in its class, ZyXel's adapters require grounded electrical receptacles because they transmits data on any two pairs of wires on a three-wire electrical cable: Line/Neutral, Line/Ground, Neutral/Ground, and so on. Non-MIMO powerline adapters have just two-prong adapters, but they deliver much lower performance, as you'll see in this product roundup, which also contains much more information on the technology.
One of the other drawbacks of powerline adapters is that they shouldn't be plugged into a surge suppressor (the surge suppressor will identify data traveling over the powerline as noise and try to filter it out). It's easy enough to plug the adapter straight into the wall, versus a power strip, but I have a whole-house surge suppressor installed in my circuit-breaker panel. When I tested the PLA5405, I saw disappointingly slow performance: Where TechHive freelance reviewer Denny Arar saw TCP throughput of more than 100Mbps while benchmarking this adapter in her home, I got a miserly 27.4Mbps (and that dropped to just 22.7Mbps when I enabled encryption between the two adapters).
I can't easily uninstall the whole-house surge suppressor (nor would I want to), so I walked over to the other side of my property and retested the pair of PLA5405 adapters in the house where my daughter lives. This is an older home, built in 1954, and most of its wiring is not grounded. But when we had a devastating water leak a couple of years ago, I took the opportunity to rewire the half of the house that needed its drywall replaced. If I'd been more sensible, of course, I would have hard-wired Ethernet cable through those walls so that I could get closer to gigabit speeds (coulda, woulda, shoulda...).
Anyway, when I plugged the PLA5405 adapters into my daughter's router, I saw TCP throughput of 91.8Mbps with encryption enabled. Not having a whole-house surge protector at that location made a huge difference in powerline-networking performance.