Correct SNIR computation units I would like to know the correct units to make a SNIR computation.

I am using the following formula:

$$
\text{SNIR} = \frac{1}{\frac{1}{\text{SNR}} + \frac{1}{\text{CIR}}}
$$

I have SNR in dB and CIR in dBm.

Shall I convert SNR to dBm to get the SNIR in dBm, or the CIR to dB to get the SNIR in dB, or there is no need to make the units change?.

I want to use the SNIR to compute a BER which is $\approx \frac{1}{4\textrm{SNR}}$

Regards
You'll have to convert back into linear units before you can evaluate the SINR formula.

${\textrm{SNR}_{linear}=10^{\big(\frac{\textrm{SNR}_{dB}}{10}\big)}}$ and likewise for CIR...

${\textrm{SINR}_{dB}  = 10 \log_{10}(\frac{1}{\frac{1}{\textrm{SNR}}+\frac{1}{CIR}}})$

${BER = \frac{1}{4{\textrm{SINR}}_{linear}}}$