An improvement in DBR named as EEDBR was proposed by A Wahid et al. in . In EEDBR, a sender node maintains depth, residual energy and ID information of its neighbours. Neighbours with smaller depth are selected and their list of IDs is included in data packet sent by sender. Receiving nodes hold the packet for holding time which is based on its residual energy Er. This may create problems as two nodes with same residual energy would have same holding time and could transmit at the same time. Moreover, EEDBR involves more number of hops in forwarding process and eventually brings increased delay and enhanced energy consumption. Hop-by-Hop Dynamic Addressing Based (H2-DAB)  routing protocol is another localization free protocol. In H2-DAB, depending on the depth of nodes, different size of addresses are given to different nodes. Deeper nodes have large size address and shallower nodes have less size address. Connectivity based Routing Protocol (CRP) protocol is proposed in  in which next forwarder node is directly related to Connectivity Index (CI) of neighbour node. where CI is defined as “number of neighbouring nodes closer to sink from a forwarding node”. Hop count based cross layer approach Channel Aware Routing Protocol (CARP) is proposed in . On the basis of recent history of successful transmissions a particular node is selected a next forwarder. CARP is hop count based protocol with varying power levels.