UCRTD: An Unequally Clustered Routing Protocol Based On Multi Hop Threshold Distance for Wireless Sensor Networks

Cluster head (CH) nodes near the base station (BS) die prematurely due to the need to perform more communication tasks, which can lead to disruption of network connectivity and makes it difficult to achieve the goal of load balancing in Wireless Sensor Networks (WSNs), this problem is known as hot spot problem. To solve this problem, non-uniform clustering strategies have been proposed. However, all the current related non-uniform clustering protocols have some drawbacks, such as the lack of a theoretical basis for the value of the multi-hop threshold distance between clusters, the limited attention to the data transmission process, and the insufficient load balancing of the protocols in the face of complex and variable networks. Based on the above problems, we propose an unequally clustered routing protocol based on multi-hop threshold distance (UCRTD) for WSNs. First, this paper analyzes the energy-saving threshold distance for multi-hop communication in conjunction with the energy consumption model of WSNs, and based on the multi-hop energy-saving threshold distance, a strategy for selecting the best energy-saving relay node is proposed. In intra-cluster communication, considering that medium-sized networks form larger clusters, cluster members (CMs) within the cluster that are farther away from the CH take multi-hop communication. For inter-cluster communication, to maximize the network lifetime, the most energy-efficient CH node with the highest residual energy is selected in the routing phase for alternate multi-hop transmission, and this strategy effectively prolongs the network lifetime and also ensures the load balance of the network. Simulation results show that the proposed UCRTD effectively prolongs the network lifetime and maintains good load balancing under multiple network environments when compared with four existing EEUC, EBUC, EADUC, and EAUCA unequal clustering protocols as well as LEACH protocol.