Maximizing Spectral efficiency instead of maximizing SINR in RI selection in 5G NR toolbox

Hi all,

I've noticed that the new version of the 5G Toolbox includes two different algorithms for calculating Rank Indication (RI): 'MaxSINR' and 'MaxSE'. The 'MaxSINR' algorithm selects the RI based on maximizing the SINR, while 'MaxSE' selects it based on maximizing spectral efficiency.

I was under the impression that the standard approach was to select the rank that maximizes SINR. Could anyone clarify the rationale behind including both algorithms and when one might be preferred over the other?

Thanks a lot

Answer 1

[Shashi Kiran]

Hi @Jake,

I understand that you want to know the difference in MaxSINR and MaxSE.

According to this MATLAB 2024a documentation,

https://www.mathworks.com/help/5g/ug/5g-nr-downlink-csi-reporting.html

the hRISelect function in MATLAB is used for selecting the Rank Indicator (RI). By exploring the example with the command,

openExample('5g/NRDownlinkCSIReportingExample')

you can observe differences in the implementation of MaxSINR and MaxSE.

MaxSINR

• Purpose: MaxSINR is important in environments with high interference or noise, as it ensures strong and reliable communication by maintaining high signal quality.
• Functionality: The riSelectPMI function in hRISelect computes the SINR for different ranks and selects the one with the highest SINR. This selection process considers SINR values across subbands and layers, as well as different codebook types.

MaxSE

• Purpose: MaxSE is ideal for maximizing data throughput, particularly in bandwidth-constrained environments, by achieving high data rates and efficient spectrum usage.
• Functionality: The riSelectCQI function in hRISelect evaluates modulation and coding efficiency by selecting the best CQI and PMI for each rank. It uses spectral efficiency values from a CQI table and considers the estimated block error rate (BLER) to determine the optimal rank for maximum efficiency.

If you need strong and reliable communication in noisy or interference-heavy areas, choose MaxSINR.

If maximum speed and spectrum efficiency is needed, go with MaxSE.

Refer the below MATLAB 2024a documentation for further help.

1. https://www.mathworks.com/help/5g/ug/5g-nr-downlink-csi-reporting.html#NRDownlinkCSIReportingExample-1

Hope this helps.