Hybrid precoder
A method employing linear precoding and non-linear precoding for transmitting data between at least two transmitters and a plurality of receivers via a plurality of communication channels over a plurality of subcarrier frequencies, the method comprising the procedures of transmitting by either one of said at least two transmitters, at least two training signals to respective said receivers; receiving by respective said receivers, said at least two training signals; evaluating channel characteristics of at least part of said communication channels, according to said at least two training signals; determining a precoding scheme selection that defines for at least part of said communication channels, over which of said subcarrier frequencies, said data transmitted shall be precoded using either one of linear precoding and non-linear precoding, according to evaluated said channel characteristics; precoding said data according to determined said precoding scheme selection; and transmitting said data according said precoding scheme selection.
1. A transmitter-initiated gain adjustment method employing precoding for at least one of mitigating and cancelling cross-talk, performing gain coordination between at least one of at least two transmitters that define a transmitter side and respective at least one receiver of at least two receivers that define a receiver side that are communicatively coupled via a plurality communication channels over a plurality of subcarrier frequencies, the method comprising the procedures of:
calculating precoding coefficients for said subcarrier frequencies, at said transmitter side;
for at least part of said subcarrier frequencies, determining a gain scaling factor based on calculated said precoding coefficients, normalizing a respective transmitted output signal from each of said at least two transmitters, limited by respective power spectral density (PSD) values; and
applying, in a time coordinated manner, said gain scaling factor and said precoding coefficients to at least one of said at least two transmitters and respective said gain scaling factor to at least one of said at least two receivers, according to respective determined said gain scaling factor, wherein said applying includes said transmitter side conveying information pertaining to said gain scaling factor to said receiver side.
2. The method according to claim 1 , further comprising a procedure of coordinating a time at which said procedure of applying said gain scaling factor at said receiver side, coincides with use of updated calculated said precoder coefficients at said transmitter side, via a synchronization protocol.
3. The method according to claim 1 , further comprising a procedure of communicating a coarse gain correction to said gain scaling factor and then a fine gain correction to said gain scaling factor, with respect to a plurality of said subcarrier frequencies, from said transmitter side to said receiver side.
4. The method according to claim 1 , wherein said gain scaling factor is different for at least some of said subcarrier frequencies.