Generally, MIMO System capacity is proportional to no. of channel coexistence at a time(or power allocated to no. of channels). Power allocation in MIMO system depends whether the Channel State Information (CSI) is known at the transmitter or not. In case, The CSI is not known at the transmitter, the power is allocated equally across all the transmitting antenna. On the other hand, when the CSI is known at transmitter, power is allocated using standard water-filling method, which inherently checks the singular values of channel matrix between Tx. and Rx.. Depending on fading condition of the channel (which in-turn results in variation in parameters like the rank and condition number) the power is allocated. Here, a sample code is allocated for MIMO water-filling algorithm.Â
Use and run "Test waterfill" and "power_waterfill" code for basic understanding of the algorithm. "Ergodic_waterfill_capacity" is more generalized code.