Coding theory

Coding theory deals with the properties of codes, and thus with their fitness for a specific application.

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There are two classes of codes.

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• Source Coding
• Channel Coding

The first is Source Encoding which attempts to compress the data from a source in order to transmit it more efficiently. We see this in practice every day on the Internet where the commom "Zip" data compression is used to reduce the network load and make files smaller. The second is Channel Encoding. This technique adds extra data bits, commonly called parity bits, to make the tranmission of data more robust to disturbances present on the transmission channel. There are many application that the ordinary user is not aware of that utilize channel encoding. A typical music CD has powerful BCH block codes to correct for scratches and dust. In this application the transmission channel is the CD itself. Cell phones also use powerful coding techniquie to correct for the fading and noise of high frequency radio transmission. Data modems, telephone transmission and of course NASA all employ powerful channel coding to get the bits through.

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Coding theory: Source Encoding ►