Forwarding function in iAMCTD is defined differently for different depth regions. SQI based forwarding function is defined in Equation (15a). (15a)SQI=LSNR×Erli In this equation li is depth difference between two successive nodes. LSNR is Localization free Signal to Noise Ratio defined in  and given by the following equation. (15b)LSNR=PtA(l,f)×N(f) where Pt is transmitted power and (A()×N()) is the attenuation noise product factor, which is product of path loss and ambient noise. A(l,f) is the sum of absorption coefficient (Abc) and scattering coefficient (Sc) whose minimum and maximum values for different depth thresholds are given in Table 1.