For example, it is studied heavily for IEEE 802.11n (MIMO) where knowing the channel allows recovery of the two or more streams which will be received on top of each other on each antenna.
The name zero-forcing corresponds to bringing down the intersymbol interference (ISI) to zero in a noise-free case.
Thus the combination of channel and equalizer gives a flat frequency response and linear phase
In reality, zero-forcing equalization does not work in most applications, for the following reasons: This second item is often the more limiting condition.
These problems are addressed in the linear MMSE equalizer[2] by making a small modification to the denominator of
This is intended to remove the effect of channel from the received signal, in particular the intersymbol interference (ISI).
The zero-forcing equalizer removes all ISI, and is ideal when the channel is noiseless.
A more balanced linear equalizer in this case is the minimum mean-square error equalizer, which does not usually eliminate ISI completely but instead minimizes the total power of the noise and ISI components in the output.