Latency —
Satellite Internet Limited by Physics
The milliseconds of delay caused from bouncing data off a satellite 23,000 miles away can have an impact on some applications.
Satellite Internet: Latency
is the amount of delay, measured in milliseconds, that occurs in a round-trip data transmission. Not directly related to speed, latency can be an issue with all networks and every type of Internet connection, including satellite networks. It’s 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 introduced.
It’s a Physics Thing
Even when traveling at the speed of light, 186,000 miles per second, it takes a certain amount of time for the signal to make the journey. 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 over 90,000 miles. Depending on your latitude, this distance to the satellite could be even greater. The physics involved account for approximately 500 milliseconds of latency, a limitation shared by all satellite providers. But dig a little deeper, and the story gets more interesting.
Network Induced Latency
In addition to transmission times, there are other factors that contribute to the total latency experienced by the end user. These include quality of internal network, IP/satellite translation overhead, speed of upstream connections, and most importantly, congestion of the satellite network itself. At Skycasters we refuse to compromise the performance of our network by oversubscription. As a result, our users typically experience total latency of under 700ms. Compare that to the 1200-1700ms of other oversubscribed satellite ISPs, and you will quickly understand the Skycasters difference.
Terminal emulators without local-echo (such as Citrix) can also be affected by latency, depending on the underlying application and configuration. If you have an application that is particularly sensitive to latency—such as online gaming—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.