Summary:
Our purpose is to highlight the special features of using multiple antennas on both the transmitter side and the receiver side, in a wireless communication system. Our presentation begins historically, with the emergence of communication systems that use electrical signals and the concepts born in this process. Today's research tests are on 5G systems and MIMO have their own place in the persistent search for ways to operate at high data rates.
A major problem in the operation of previous technologies is the existence of multiple paths of a signal within the channel. MIMO are making the leap, and basically rely on this condition, to offer the maximum of available degrees of freedom in communication. We focus on the explanation of these natural phenomena and on the mathematical formalism that is followed.
A new technology that develops the framework for the use of multiple antennas is the massive MIMO, with which a base station can be equipped with "too many" antennas to simultaneously serve a large amount of users - with multiple or not antennas at their terminals. It is an active research sector, which also wants to offer the conditions for high quality services.
