# Is there any technology or method that let user $Z$ knowS which message is $x_B$ and which is $x_C$

There is a device $$Z$$ which transmits the signal $$x_A$$ and receives the informations $$x_B$$ and $$x_C$$ simultaneously.

I think when this device receive the signal,it won't know which is $$x_B$$ and which is $$x_C$$,because the SINR of receiving $$x_B$$ and the SINR of receiving $$x_C$$ is too small,is there any method to avoid this situation?

The only method i know is that transmitting the $$x_B$$ and $$x_C$$ in different frequency band,but is there any method that can solve this problem?Can we design the beamforming of the device ,which transmits signal to device $$Z$$, to solve this problem?

By the way,device $$Z$$ uses MIMO,multiple input (antennas),multiple output (antennas)

• You can use successive interference cancellation. Check it out. – BlackMath Sep 11 at 23:09
• is there any successive interference cancellation about designing beamforming? – XM551 Sep 11 at 23:11
• SIC has nothing to do with beamforming. It's a method to decode signals in interference channels. You can use beamforming I guess, but this requires both users which generate the signals to be equipped with multiple antennas. – BlackMath Sep 11 at 23:32
• @BlackMath If device $C$ and device $B$ want to sent the message $x_C$ and $x_B$ to device $Z$,is designing the beamforming of device $C$ and device $B$ helpful for decreasing the SINR for device $Z$ receiving the $x_C$ and $x_B$? – XM551 Sep 11 at 23:47
• Probably you need to design both beamformers jointly such that the signals are orthogonal at $Z$. I haven't worked on beamforming before. You need to do more reading. – BlackMath Sep 12 at 9:05