I still have some queries related to layer mapping and precoding.
Since we know that layer mapping is break the data symbols corresponding to CodeWord into multiple layer parts and transmit different parts over different antennas. The word of layer in general what is a layer? because most people confused with word layer because they think it is OSI layers.
For precoding if we use 1 layer and assume 4x4 MIMO is configured in 5G, signal data symbol is emitted from each of the transmit antennas with appropriate gain like signal power is maximized at the reception, right? If that so, this means that at reception the signal data symbol after precoding cannot simultaneously maximize the signal level at all of the receive antennas.
To maximize the signal level, we need to increase number of layers?