Soil moisture estimation using the sentinel-1 dual pol (VV, VH) SAR data

Hello everyone,
I am new in soil parameter analysis. I wanted to know some methodologies for estimating the soil moisture (vol%) using the sentinel-1 dual pol (VV, VH) SAR data. Beside this I am having information such as NDVI, elevation, soil type and soil moisture(ground truth). Can anyone suggest some methodology (preprocessing, algo, evaluation). Also I want some guidance regarding the use of H-alpha decomposition for the same.

there are already many topics on this

You will soon see that there are many approaches of doing it. Many are based on field measurements and images from both rainy and dry periods.