NR technology -- MIMO

1. What is? MIMO

MIMO：Multiple-Intput Multiple-Output, That is, multiple input multiple output system , The input and output here are relative to the antenna system composed of transmitting antenna and receiving antenna .
The usual communication system is single sending and single receiving , That is to say SISO：Single-Input Single-Output

2.SISO The information transmission rate of the system is limited by Xiangnong theorem .

Shannon gives the interference of Gaussian white noise , The maximum value of the information rate for error free transmission on the channel with limited bandwidth , That is, channel capacity . Shannon's formula is as follows ：

B That's bandwidth ,S Is the signal power ,N Is the noise power ,S/N It's the signal-to-noise ratio .
The channel capacity between a single transmitting antenna and a single receiving antenna is limited by Xiangnong formula , Want to further improve the channel capacity under the same spectrum bandwidth , Adopt multi antenna technology .

3. Why? MIMO Improve the signal rate

More in, more out ,(N_t Enter into N_r Out ), among h Channel gain ,s It's the originator signal ,y Is to receive the signal .

Conclusion ：

1. The rank of the matrix is equal to the rank of the row vector group constituting the matrix , That is, the number of vectors contained in the maximum linear independent vector group of the row vectors constituting the matrix .
2. Those who have t A transmitting antenna ,r Root receiving antenna MIMO System , Channel matrix H The maximum rank of is min(t,r), At most, it can be transmitted in parallel min(t,r) Road data .

4. Spatial multiplexing and transmit diversity

Spatial reuse ：SM：Spacial Multiplexing .
If the wireless channel quality is better , And the rank of the channel matrix is greater than 1, Send multiple different data in parallel , It can improve the throughput of data transmission , This is spatial reuse .
Send diversity ：TD：Transmit Diversit
The receiver has only one antenna , The transmitter sends multiple identical data in parallel , It can improve the reliability of data transmission , Send diversity .

notes ： In this paper, the reference 《 Explain profound theories in simple language — Communication principle 》 This book , Author Chen Aijun , If there is infringement , Please inform , Delete now .