Our goal is to develop techniques to mitigate the

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: ent past were received incorrectly. 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 with bursts. 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 1 Graphical codes are sometimes also called “probabilistic codes” in the literature, for reasons we can’t get into here. 2 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...
View Full Document

This document was uploaded on 02/26/2014 for the course CS 6.02 at MIT.

Ask a homework question - tutors are online