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Our goal is to develop techniques to mitigate the effects of both the BSC and burst
errors. We’ll start with techniques that work well over a BSC and then discuss how to deal
A BSC error model is characterized by one number, p. We can determine p empirically
by noting that if we send N bits over the channel, the expected number of erroneously
Graphical codes are sometimes also called “probabilistic codes” in the literature, for reasons we can’t get
The “white” part of this term refers to the variance being the same over all the frequencies being used to
communicate. SECTION 6.2. THE SIMPLEST CODE: REPLICATION 3 received bits is N · p. Hence, by sending a known bit pattern and counting the fraction or
erroneously received bits, we can estimate p. In practice, even when BSC is a reasonable
error model, the range of p could be rather large, between 10−2 (or even a bit higher) all the
way to 10−10 or even 10−12 . A value of p of about 10−2 means that messages longer than a
100 bits will see at least one error on average; given that the typical unit of communication
over a channel (a “packet”) is generally at le...
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This document was uploaded on 02/26/2014 for the course CS 6.02 at MIT.
- Fall '13