MIMO directional modulation M-QAM precoding for transceivers performance enhancement

The increasing mobile data traffic requires network coverage expansion and rate enhancement. However, this demands more power and results in environmental pollution. As a solution, directional modulation can be used to provide efficient and interference-free communications. In this work, we geometrically model the extended detection regions of M-QAM modulation for M = 4, 8, 16, 32 and use these modeled regions to design energy efficient symbol-level precoders for an interference-free MIMO directional modulation transceiver. We formulate and transform the precoder design problems into linearly constrained quadratic programming optimization problems. The simulation results show that compared with the benchmark schemes, directional modulation results in lower power consumption and symbol error rate using the less stringent extended detection regions and interference-free capability, respectively.