Massive MIMO is a type of multiple-input multiple-output (MIMO) technology that uses a very large number of antennas to improve communication performance. It is sometimes referred to as large-scale MIMO or distributed MIMO.

Traditional MIMO systems use a small number of antennas (usually two) to transmit and receive signals in multiple directions at the same time. Massive MIMO systems use a much larger number of antennas, which can improve communication performance in a number of ways.

One benefit of massive MIMO is that it can increase the spectral efficiency of a communication system, which is a measure of how much data can be transmitted over a given frequency band. Massive MIMO can also improve the energy efficiency of a system since less power is required to transmit a given amount of data.

Another benefit is that massive MIMO can improve the reliability of communication since a large number of antennas can provide a more robust signal. And finally, massive MIMO can also improve the capacity of a communication system, since more users can be supported with the same amount of resources.

Massive MIMO is a promising technology for the next generation of wireless communication systems. It has the potential to improve the performance of these systems in a number of ways and is currently being studied by a number of research groups around the world.