Spatial peak power minimization for relaxed phase M-PSK MIMO directional modulation transmitter

The burst in media content and access to smart phones has created an increasing demand for data. At the same time, powering up mobile base stations contributes notably to CO2 footprint. To address these issues, we need to design energy efficient communication systems with higher data rates while considering practical limitations. As a solution, we design an optimal M-PSK directional modulation precoder with spatial peak power minimization where the communicated symbol on each receiving antenna is placed in the optimal location of a predefined region. Such an approach allows less stringent design and results in further energy efficiency. In this work, we characterize the relaxed region, formulate the optimal symbollevel precoder design problem, and transform it into a standard form. The simulation results show that the relaxed design reduces the consumed power while the symbol error rate increment at the receiver due to the relaxed phase design is negligible.