carrier index and their correspond frequency

[evileleven]

csidata = csiread.Intel(dat_file, nrxnum=3, ntxnum=1)

I use the above code to read CSI .dat file.
There are 30 carriers.
I want to know the indexes and their corresponding frequency.
Does index 0,1,2,3,4,...., 29 corresponds to -28,-26,..., -1,1,...27,28 ?