Please help me: Could you explain what Precoding is

Hi all,
Please can you explain what precoding is for me. If you have any document related to precoding, please share them to me. I have asked this question before but no answer so I ask for help again. Thank you very much in advance.

Thank you so much for the file. I am going to read it. Can I ask a question before reading it.

Is precoding Beamforming?

It is a method of beamforming for MIMO systems. Please have a look at Wikipedia as an introduction:

https://en.wikipedia.org/wiki/Precoding

Precoding is generalized beamforming to support multi-layer transmission in MIMO radio systems. Conventional beamforming considers linear single-layer precoding so that the same signal is emitted from each of the transmit antennas with appropriate weighting such that the signal power is maximized at the receiver output. When the receiver has multiple antennas, the single-layer beamforming can not simultaneously maximize the signal level at all of the receive antennas and so precoding is used for multi-layer beamforming in order to maximize the throughput performance of a multiple receive antenna system. In precoding, the multiple streams of the signals are emitted from the transmit antennas with independent and appropriate weighting per each antenna such that the link throughtput is maximized at the receiver output.

mazdaspring said:

Hi all,
Please can you explain what precoding is for me. If you have any document related to precoding, please share them to me. I have asked this question before but no answer so I ask for help again. Thank you very much in advance.

Click to expand...

Precoding is a form of pre-processing in which the signal is pre-distorted so that when the signal is received in receiver it will be free of interference. For example, when you transmittind signal vector X over MIMO channels you received signal vector Y=HX+n. At the receiver you need the transmitted signal X in presense of co-antenna interference. There are some method to silve this problem. for example ML detection, VBLAST detection, Lmear Equalizer, DFE Equalizer,.....
The mentioned methods are receiver based processing, but it is possible to have transmitter (Tx) processing or pre-processing. If you transmite the Linear equalizer to Tx side it is named as linear precoder. If you transmit the DEF equalizer to Tx side it will be non-linear precoder. for example Tomlinson Harashima Precoder is counter part of DFE with some modification.