In telecommunications, dirty paper coding (DPC) or Costa precoding is a technique for efficient transmission of digital data through a channel subjected to some interference known to the transmitter.
Dirty-paper coding achieves the channel capacity without a power penalty and without requiring the receiver to know the interfering signal.
By erasing and adding ink in the proper places, the writer can convey just as much information as if the paper were clean, even though the reader does not know where the dirt was.
[1] Suboptimal approximations of dirty paper coding include Tomlinson–Harashima precoding (THP) published in 1971[2][3] and the vector perturbation technique of Hochwald et al.
In 2003, Caire and Shamai[5] applied DPC to the multi-antenna multi-user downlink, which is referred to as the 'broadcast channel' by information theorists.