Unformatted text preview: ast 1000 bits long (and often bigger), such an
error rate is too high.
But is a p of 10−12 small enough that we don’t need to bother about doing any error
correction? The answer often depends on the data rate of the channel. If the channel has
a rate of 10 Gigabits/s (available today even on commodity server-class computers), then
the “low” p of 10−12 means that the receiver will see one error every 10 seconds on average
if the channel is continuously loaded. Unless we take some mechanisms to mitigate the
situation, the applications using the channel may ﬁnd this error rate (in time) too frequent.
On the other hand, a p of 10−12 may be quite ﬁne over a communication channel running
at 10 Megabits/s, as long as there is some way to detect errors when they occur.
It is important to note that the error rate is not a ﬁxed property of the channel: it depends on the strength of the signal relative to the noise level (aka the “signal to noise
ratio”, or SNR). Moreover, almost every communica...
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This document was uploaded on 02/26/2014 for the course CS 6.02 at MIT.
- Fall '13