Another localization free protocol, Adaptive Mobility of Courier nodes in Threshold-optimized DBR (AMCTD), is proposed in . In this protocol, forwarding of packet is improved and based on weight, which is function on depth, residual energy and some priority values assigned to them. An improvement in AMCTD named as improved AMCTD (iAMCTD) is proposed in  in which different routing metrics are defined for different depth regions. These metrics include Localization free-SNR (LSNR), Signal Quality Index (SQI) and Energy Cost Function (ECF) and Depth Dependent Function (DDF). Moreover hard and soft threshold based simulation scenario is adopted in which a sensed event’s value greater than hard threshold is reported to sink. Moreover, authors employed courier nodes in  for data gathering tasks. Here mobility of nodes start when certain fraction of total nodes have died, which is not efficient and full use of deployed resources. Holding time calculation process does not guarantee optimum value of holding time ensuring packet suppression and minimum end to end delay.