The SQI based forwarding function range is always in interval [0, 491.91]. The upper limit is far less than defined in previous schemes and is more comparable to the range of ECF and DDF based forwarding function. ECF based forwarding function FF is directly proportional to Er and inversely proportional to depth difference previous and current node depths Dp−Dc is defined below: (19)ECF′=[pv×RTDp−Dc]Er where RT is transmission range Er is remaining energy of a certain node. Forwarding function is directly dependent on remaining energy weighted by a factor given in square brackets whose range is described as follows: Neighbour selection process and depth threshold ensure that Dth<(Dp−Dc)<RT. Initially Dth is set to 60 m and is subsequently changed to 40 m and 20 m after certain percentage of deaths, and RT is constant =100. So for above mentioned values factor in square brackets in Equation (19) has range, from 1 to 1.66 for dth=60, from 1 to 2.5 for dth=40 and from 1 to 5 for dth=60. This eventually gives value of forwarding function always between 0 to 5×Eo which is comparable with the range of SQI′. DDF is also modified taking newly defined and linearized version of SQI. (20)DDF′=SQI′×liDi