1. What is MU- MIMO？

MU-MIMO: Multi-User Multiple Input Multiple output.

The usual communication system is SU-SISO，Single-user Single Input Single Output.

MU-MIMO is a wireless communication technology that uses multiple antennas to improve communication by simultaneously creating multiple connections to the same device.

2.SU-SISO system information transmission rate is limited by the Shannon formula.

Claude Elwood Shannon gives the maximum value of the information rate of no error transmission on the channel of white gaussian noise interference, which is the channel capacity.

The channel capacity between the single -launch antenna and the single -receiving antenna is limited by the Shannon formula. If you want to further increase the channel capacity of the channel under the same spectrum bandwidth, multi -antenna technology must be used.

3.MU-MIMO technology

MU-MIMO is based on multi-antenna technology. The physical layer of this technology is multi-antenna technology. Multi-antennas can achieve a variety of technologies, not just MU-MIMO

The implementation of MU-MIMO is combined with beam forming. There are two ways to implement the beam forming. One is the smart antenna beam forming, and the other is a beam forming based on the omnidirectional antenna.

There are many concepts of MIMO, for multiple antennas, mainly two concepts: diversity and reuse. If there are multiple channels, such as two channels, if the two channels are transmitted to the same information, then it is diversity. If the two channels are transmitted to two different information, it is reused. MIMO is actually a combination of diversity and reuse, and beam forming is a distribution. 

Based on MIMO technology, you can sent more and receive more. The basic MIMO is that one sender has two antennas, one recipient has two antennas, the sender sends two antennas at a time, the recipient uses two antennas at a time, and then the transmission rate is twice. This is the MIMO technology made in the 802.11n era.