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Satellite Internet: Latency

Not directly related to speed, latency can be an issue with all networks including satellite networks.

Latency is the amount of delay, measured in milliseconds, found in a round-trip data transmission. Latency is caused by several factors including the number of times the data is handled along the transmission path (by routers or servers for example).

Each time a data packet is handled by a device along the path (called a "hop") several milliseconds of latency are induced. More importantly in the satellite world, latency is caused by the distance that the signal must travel.

Because satellite transmissions traverse a very long distance, satellite has a higher latency than a typical terrestrial connection. The GEO satellites used for two-way Internet service are located approximately 23,000 miles above the equator. This means that a round-trip transmission travels 23,000 miles to the satellite, 23,000 miles from the satellite to the remote site, and then as the TCP/IP acknowledgment is returned, another 46,000 miles on the return trip for a total round trip of about 92,000 miles. This is roughly equal to a signal traveling around the circumference of the Earth four times. Even at the near light-speed of the transmission, this accounts for more delay than found in a terrestrial network.

Most Internet applications including web browsing, email, FTP etc. work in their normal manner even when traversing this long distance and user experiences are very positive. Certain applications, such as Voice-Over-IP are affected but also work. Some applications, such as online-gaming are not recommended.

Citrix, and any other terminal emulator without local-echo, can also be affected by latency depending on the underlying application and configuration. If you have an application that is particularly sensitive to latency, satellite may not work for you.

It is recommended that customers check with their software vendor to confirm how specific applications are affected by latency. Our sales engineers can give you an idea of what to expect after analyzing your requirements.
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