On the trade-off between transmit and leakage power for rate optimal MIMO precoding

In this paper, we study the interdependency between leakage reduction and transmit power control for rate maximization in leakage based precoding (LBP) for a multi user multiple-input multiple-output (MU-MIMO) scenario. We propose a LBP scheme which provides the rate optimal precoding for each MIMO link under a joint leakage and transmit power constraint and derive an iterative closed form solution for it. Depending on the constraints and the strength of the leakage power, the leakage power and/or the transmit power needs to be adjusted. Any leakage level between the egoistic case, where the leakage is not reduced at all, and the altruistic case, where the leakage is minimized, can be achieved. This allows to optimize the network performance in a MU-MIMO setup by optimally choosing the trade-off between leakage power and transmit power constraints. Using numerical simulations, we show the interdependency between the leakage power and the transmit power and demonstrate the gain we can achieve with the optimal trade-off.