Waterfilling power allocation applied in block-diagonalization Multi-User MIMO precoding technique

Next generation of mobile communications (5G) comes with high throughput demands (up to more than 10 Gbps). From a radio access point of view, this requires using spatial multiplexing techniques that allow reaching these rates and are suitable for cases where the transmitter has a large number of antennas. The challenges are even bigger when it comes to spatially multiplexing multiple mobile stations in the same time-frequency resource, a technique known as MU-MIMO (MultiUser MIMO). The Block Diagonalization technique shows a strong performance in MU-MIMO scenarios by eliminating the inter-user interference. This method also presents good flexibility in terms of intra-user and inter-user transmission energy allocation. This paper analyzes the performances - in terms of sum-capacity - of the downlink Block Diagonalization MU-MIMO technique when paired with the waterfilling power allocation mechanism. The use cases considered in the performed simulations are aligned to those considered in the 5G networks: up to 128 transmit antennas at the base station side, up to 64 mobile users spatially multiplexed and up to 16 antennas for each mobile station.