In telecommunication

Telecommunication

Telecommunication is the transmission of information over significant distances to communicate. In earlier times, telecommunications involved the use of visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded...

s, dirty paper coding (DPC) is a technique for efficient transmission of digital

Digital

A digital system is a data technology that uses discrete values. By contrast, non-digital systems use a continuous range of values to represent information...

 data

Data

The term data refers to qualitative or quantitative attributes of a variable or set of variables. Data are typically the results of measurements and can be the basis of graphs, images, or observations of a set of variables. Data are often viewed as the lowest level of abstraction from which...

 through a channel subjected to some interference

Interference (communication)

In communications and electronics, especially in telecommunications, interference is anything which alters, modifies, or disrupts a signal as it travels along a channel between a source and a receiver. The term typically refers to the addition of unwanted signals to a useful signal...

 known to the transmitter. The technique consists of precoding

Precoding

Precoding is a generalization of beamforming to support multi-layer transmission in multi-antenna wireless communications. In conventional single-layer beamforming, the same signal is emitted from each of the transmit antennas with appropriate weighting such that the signal power is maximized at...

 the data in order to cancel the effect caused by the interference.

Dirty-paper Coding achieves the channel capacity

Channel capacity

In electrical engineering, computer science and information theory, channel capacity is the tightest upper bound on the amount of information that can be reliably transmitted over a communications channel...

, without power penalty and without requiring the receiver to gain knowledge of the interference state.

Note that DPC at the encoder

Encoder

An encoder is a device, circuit, transducer, software program, algorithm or person that converts information from one format or code to another, for the purposes of standardization, speed, secrecy, security, or saving space by shrinking size.-Media:...

 is an information-theoretic

Information theory

Information theory is a branch of applied mathematics and electrical engineering involving the quantification of information. Information theory was developed by Claude E. Shannon to find fundamental limits on signal processing operations such as compressing data and on reliably storing and...

 dual of Wyner-Ziv coding at the decoder

Decoder

A decoder is a device which does the reverse operation of an encoder, undoing the encoding so that the original information can be retrieved. The same method used to encode is usually just reversed in order to decode...

 .

History

Instances of dirty paper coding include Costa precoding (1983) , Tomlinson-Harashima precoding (1971) and the vector perturbation technique of Hochwald et al. (2005) .

Design considerations

DPC and DPC-like techniques requires knowledge of the interference state, such as channel state information

Channel state information

In wireless communications, channel state information refers to known channel properties of a communication link. This information describes how a signal propagates from the transmitter to the receiver and represents the combined effect of, for example, scattering, fading, and power decay with...

 of all users and other user data. Hence, the design of a DPC-based system should include a procedure to feed side information to the transmitters.

Applications

Recently, there has been interest in DPC as a possible solution to optimize the efficiency of wireless network

Wireless network

Wireless network refers to any type of computer network that is not connected by cables of any kind. It is a method by which homes, telecommunications networks and enterprise installations avoid the costly process of introducing cables into a building, or as a connection between various equipment...

s, in particular multiuser MIMO

MIMO

In radio, multiple-input and multiple-output, or MIMO , is the use of multiple antennas at both the transmitter and receiver to improve communication performance. It is one of several forms of smart antenna technology...

 networks and into an interference aware coding technique for dynamic wireless networks .

Recently, DPC has also been used for "informed digital watermarking

Digital watermarking

Digital watermarking is the process of embedding information into a digital signal which may be used to verify its authenticity or the identity of its owners, in the same manner as paper bearing a watermark for visible identification. In digital watermarking, the signal may be audio, pictures, or...

".

See also

• Multiple-input multiple-output communications
• Advanced MIMO communications
• Cognitive radio
  Cognitive radio
  A cognitive radio is a kind of two-way radio that automatically changes its transmission or reception parameters, in a way where the entire wireless communication network -- of which it is a node -- communicates efficiently, while avoiding interference with licensed or licensed exempt users...