Dirty paper coding

In telecommunications, dirty paper coding (DPC) is a technique for efficient transmission of digital data through a channel subjected to some interference known to the transmitter. The technique consists of precoding the data in order to cancel the effect caused by the interference.

The term 'dirty paper coding' comes from Max Costa who imagined a paper which is partially covered with dirt that is indistinguishable from ink. The theorem says that if the writer knows where the dirt is to start with, she can convey just as much information by writing on the paper as if it were clean, even though the reader does not know where the dirt is. In this case the dirt is interference, the paper is the channel, the writer on the paper is the transmitter, and the reader is the receiver. In information-theoretic terms, dirty-paper coding achieves the channel capacity, without a power penalty and without requiring the receiver to gain knowledge of the interference state.

Note that DPC at the encoder is an information-theoretic dual of Wyner-Ziv coding at the decoder .