  Achieving an increase in the spectral efficiency (SE) has always been a major
driver in the design of communication systems. The use of MIMO techniques in
mobile communications has achieved significant benefits in improving the system
throughput. The basic underlying concept of MIMO is to exploit the signal and
channel characteristics to eliminate interference between multiple
transmissions. Departing from the work carried out under the industrial
projects \cite{NGW,Henarejos}, we extend the results provided in their
respective reports. The goal is to increase the SE without an increment of
radiated energy without any Channel State Information at Transmitter (CSIT) and
feedback at the transmitter and maintaining a very low computational complexity
at the receiver. Although a priori additional power is required to increase the
SE, we demonstrate that the proposed Polarized Modulation (PMod) scheme
exploits the polarization diversity reducing the required EbN0 and adding an
extra bit. We also introduce two receivers to demodulate this scheme of
different computational complexities. We describe a Near Optimal Detector (NOD)
which achieves almost the same performance as the optimal detector based on the
Maximum Likelihood Detection (MLD), but with lower computational complexity.
Finally, the results demonstrate that the PMod requires less EbN0 compared with
the single polarization case, guarantees the robustness in the presence of the
cross-polarization and validates that PMod can multiplex two streams of
different Quality of Service (QoS).
