# Tutorial 27 – Finding MIMO

Description: A comprehensive, easy to read tutorial on MIMO.

###### 9 comments on “Tutorial 27 – Finding MIMO”
1. JB says:

hello Charan Langton,

I first thank you for your insightful tutorial. however in fig 27.4 about SISO and MIMO capicty Vs SNR comparison, I think there was a mistake in legends marking. for example at 10dB of SNR SISO is marked to be with high data rates than MIMO. I stand to be corrected if I am the one with wrong interpretation.

• admin says:

Thanks a bunch, I will try to fix the label.

2. Charan L. says:

Fig. 27-3 in MIMO tutorial is mislabeled. JB, you are right that the bottom curve is the SISO curve and as we add greater dimensionality, the capacity rises.

The top curve and the bottom curve, the labels are reversed.
Thanks for pointing it out. – Charan

3. Vision 2020 says:

Where can I get the code for 4*4 mimo systems ? I want to implement it to learn about it.

• Charan L. says:

What exactly do you want to simulate in Matlab?
Charan

4. Alonso says:

I’m lost with you tutorial 27 on page 28 (Example 4) in the begining of page, I dont know how you calculate the figures 1,26 and 9,73 1,875 1,343 for each channel. I need to know it because for distribution the power. I apppreciate so much your help, your tutorial is fantastic. Thank in advance – gonsito @ gmail .com

5. Glenn Keller says:

Could you kindly clarify a point in the MIMO tutorial with regards to 27.1 which expresses SNR in dB? My understanding of the Shannon theorem is that SNR is expressed as a dimensionless power ratio, but not in dB. Would not the Capacity in 27.1 equate to 2 b/s/hz?

• Glenn Keller says:

My mistake – apologies. You have the calculations correct. What threw me off was that 10log10(10) = 10. I thought that you were using the SNR in dB in the equation but you convert the dBs back to a power ratio before calculating C. Sorry…

6. Sandeep Mukherjee says:

Great tutorial. I just have one doubt, On page 18 (equation 27.28) you are writing R_xx = P_T I_3 (where I_3 is a 3X3 identity matrix) and P_T is the “Total Power of the system”. Since, each diagonal element of R_xx contains the power transmitted by each transmitting antenna, in this case, the total transmitted power becomes: P_T + P_T + P_T = 3P_T. So shouldn’t the equation read R_xx = (P_T/3) I_3 if we want to make the total transmitted power to be P_t? Similarly, in the case were the powers are in the ratio 1:2:3, the covariance matrix should be R_xx = (P_T/6)*[1 0 0; 0 2 0; 0 0 3]? Thanks in advance.

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