Ramblings of Narc

Leo Notenboom of Ask Leo! has written a thoroughly useful article about wireless Internet connectivity. In the comments section, a reader pointed out the omission of satellite Internet from the list. The comment read thusly:

Great subject! Informative answers! But don’t forget about Satellite internet. The prices are comming down. I live in the country and have only dial-up. I’ve checked some different options and I found I can get broadband high speed for about $15 a week and not have to buy anything.

This was my reply, and I considered it so good (and long-winded, but that’s another story) that it was worth reposting on this blog (with some cleanup and additional formatting):

Satellite Internet is, indeed, another wireless connection type, and it’s a somewhat older one than most of the ones discussed in this article, thus we could say the technology is “proven”. However, its low adoption rate is not solely because of its price.

Satellite connections suffer from some limitations which can be hard to live with, depending on exactly how you’re using your Internet connection:

• firstly, and most importantly, satellite connections suffer from high latency. This is a function of basic physics — the satellites are far enough away from any point on the surface of Earth that it takes a non-trivial amount of time for data in the form of electro-magnetic impulses to reach them, reach the other point, and return. My current Internet connection gives me latencies on the order of 150 milliseconds, on average, from Romania (Eastern Europe) to the United States. By comparison, for satellite access you could be looking at latencies as high as 1 or 2 seconds (thousands of milliseconds!) for a round trip to a server that might be just a couple of miles away. And that’s on top of the pre-existing round trip from the other end of the satellite connection to the server you’re trying to reach.
• secondly, weather: as documented on Wikipedia, “[satellite] communications [are] affected by moisture and rain in the path of signal”; meaning, effectively, that a rainy day in the summer might leave you with a crippled, if not completely non-functional Internet connection. Add to that the likelihood of snow build-up on the satellite receiver dish, and thus the requirement of continuous maintenance, and it makes for a somewhat unreasonable connectivity solution.
• the third, least important but still potentially crippling disadvantage is that most satellite Internet providers tend to offer one-directional access only. That is, download-only (from the Internet to your computer). But all communication on the Internet, by virtue of the design of the TCP/IP protocol, is bi-directional: all packets sent must be acknowledged, and don’t get me started on the three-way handshake. What this all means is that you might still have to keep your dial-up connection and use it for the opposite direction, which will effectively slow down your communications to the rate at which your dial-up connection is capable of routing the acknowledging packets, which, although obviously smaller than the primary communication ones, are still a limiting factor.

There is also the further limitation of line of sight, specifically the communication-dampening effects of vegetation, meaning more continuous maintenance to ensure a tree (or, in a city environment, a building!) doesn’t come between your receiver dish and the satellite it’s trying to reach.

But the trifecta of latency, weather, and unidirectionality provides strong incentives to stay away from satellite connections except as a last resort. I’m also suspicious of your final statement of “not [having] to buy anything”, since contacting a satellite absolutely requires the existence of a satellite dish, but perhaps you already have that for TV.

If you’re curious, the uni-directionality limitation results from the fact that satellite communications are generally optimized for TV-like systems, wherein there is a single sender and many recipients. By contrast, an Internet connection by design is point-to-point, there being a sender-recipient pair for each such connection. This effectively results in satellites being a very poor method of transmission, having a very limited number of channels, which accounts for the relatively high cost of connection. Simply put, a satellite with, say, 1,000 channels could broadcast 1,000 TV programmes to potentially millions of viewers (who are all receiving the exact same data), or it could provide Internet access to exactly 1,000 people. Some magic is probably possible by splitting the channels into smaller ones, but the result of that will necessarily be a lowering of speed, and you may end up with a bandwidth the same as a dial-up connection but with a much higher latency.

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I didn’t mean for such a long treatise of satellite connections, but I feel I’ve done a reasonable job of describing the pitfalls there. I’d like to restate that it could still be a potential option, just not one that is likely to be reasonably priced — either in upfront or hidden costs.