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Ask Ars: What are some networking alternatives to Ethernet and WiFi?

Ask Ars looks at some alternatives to wireless networking in situations where …


Question: I rent an apartment where I can't do any substantial modifications to the rooms. There are a ton of WiFi networks competing for the same spectrum, so doing stuff like streaming video across the home network is choppy. In a perfect world, I'd run CAT-6 cable through the place and set up a gigabit Ethernet network, but that's not practical. There is coax running to each room, and I'm vaguely familiar with powerline networking. What are my networking options, and what is the performance of these technologies like?

Fortunately for you, there are multiple technology alliances and advocacy groups working at developing alternative methods for spreading the Internet to all corners of your house using existing wiring, including via coax cables and the electrical wiring in your house. Some methods may sound a little dubious, but they've gotten much more reliable in recent years. The main reason they are not widely used is that they can be pretty expensive, especially if you have multiple computers you want to connect. But if you're dedicated to shining the Internet's light into the darkest corners of your residence, one of these alternatives may be a good solution.

Powerline adapters, which use existing electrical wiring to transmit data, and MoCA adapters, which do the same thing with coax cabling, actually route and modulate signals in much the same way as WiFi networks do, with modulation and multiple signal carriers.

The system that all these types of transmission use is called orthogonal frequency division multiplexing (OFDM). In OFDM, a source can send a signal out over multiple frequencies; for example, it might have one channel at 1.03GHz, and another at 1.12GHz. Each of the carrier frequencies are modulated to represent the data they need to transmit and send out to the receiver, which recombines them into the single stream of information it was looking for.

OFDM doesn't sound terribly efficient, but it allows data sources to deal with a big problem in information transmission: noise and interference. If a data source like a powerline adapter or a wireless router detects a lot of noise in one carrier frequency, it can usually avoid that one and selectively use other non-noisy channels.

The advantage of using powerline or MoCA adapters to route your Internet traffic is that you can avoid what sounds like a crowded 2.4GHz spectrum in your immediate area. Powerline adapters transmit in the 2MHz-52MHz range, while MoCA adapters on the market use 1.15GHz-1.5GHz. MoCA, the group responsible for setting standards for MoCA adapters, also ratified MoCA 2.0 less than a year ago, so newer adapters will be able to operate between 500MHz and 1.65 GHz.

Of course, powerline and MoCA adapters are going to run into their own set of interference problems separate from your WiFi. The coax cables that MoCA adapters use can be affected by certain landline phones and microwaves, and signals in the copper wiring used by powerline adapters can be affected by circuit interrupters, transistors, and transformers. Powerline adapters are also limited to working on a single circuit, so if your house has more than one breaker box, you'll have to make sure your router and adapters are running in the same electric circle.

As far as connection quality, powerline and MoCA adapters will not be as reliable as an Ethernet connection. Powerline adapters in particular were maligned several years ago for their poor speeds and reliability, but have since come a long way. There are multiple alliances that set powerline standards, but most adapters today are rated at about 200Mbps. It's no gigabit Ethernet, but it will get you around.

Current MoCA adapters are about the same, topping out at 175Mbps combined upload and download. However, the latest MoCA 2.0 standards dictate a throughput of 400-800Mbps.

Another possible solution we have not yet mentioned is getting a dual-band 802.11n router and using its 5GHz frequency, rather than the more ubiquitous 2.4GHz. Not only would this get you away from the wireless connections of surrounding residences, but it might also protect you from the pesky microwaves and landline phones that also use it. The big problem with 5GHz wireless is signal attenuation—its effectiveness drops off significantly with distance, especially if that distance is interspersed with walls. Support for wireless-N can also be iffy to nonexistent on smartphones and various consoles.

But an advantage an 802.11n 5GHz router will likely hold over powerline and MoCA adapters is flexibility—a good dual band router runs $100-130, and multiple computers can connect to it. A 200Mbps powerline adapter kit with two adapters (one to pull the connection from a modem or router into the wall, another to pull it from the wall to your computer) is $120 or so, and only gets you a single connection. Some adapters have multiple Ethernet ports, but if you have multiple rooms in need of Internet, each additional adapter is $60-70. MoCA adapter kits are around $200, like this Netgear version (which Ars Deputy Editor Jon Stokes uses and has had great results with).

Ultimately, this is a question of which frequency in your house is going to be least crowded and which sets of wiring are the least old. For instance, you may hook up a powerline adapter only to find that it crawls even worse than your 2.4GHz WiFi, possibly because the electrical wiring is old and terrible, but a MoCA connection may breeze right along. Either way, both powerline and MoCA adapters have been moving ahead development-wise in the last few years, and are definitely worth a look if your WiFi leaves something to be desired.

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