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Different variants of LEACH algorithms are presented in the literature. A stable improved LEACH (SILEACH) algorithm, one of the LEACH variants, was proposed to overcome the problems of LEACH algorithm. Enhanced LEACH (ELEACH) and improved LEACH are other variants of LEACH algorithm which have the ability to increase the network lifetime. ELEACH utilizes distance to increase the lifetime, whereas improved LEACH increases the network lifetime using the residual energy and distance to the base station (BS). However, cluster heads selection in improved LEACH and ELEACH reduces the stability period. Generally, in many applications, network stability is considered crucial because the feedback reliability is required by the network. Recently, the SILEACH has been evaluated by assuming the BS outside the network area. In this paper, a re-evolution of the SILEACH algorithm in different environments is performed to show its effectiveness in overcoming the limitation of the ELEACH and improved LEACH algorithms. This is performed by assuming the BS inside the network area. The simulation results showed that the SILEACH significantly outperforms the two protocols in terms of the stability period and network lifetime.

Recently, increasing battery lifetime in wireless sensor networks has turned out to be one of the major challenges faced by researchers. The sensor nodes in wireless sensor networks use a battery as their power source, which is hard to replace during deployment. Low Energy Adaptive Clustering Hierarchy (LEACH) is one of the most prominent wireless sensor network routing protocols that have been proposed to improve network lifetime by utilizing energy-efficient clustering. However, LEACH has some issues related to cluster-head selection, where the selection is done randomly. This leads to rapid loss of energy in the network. Improved LEACH is a LEACH alternative that has the ability to increase network lifetime by using the nodes’ residual energy and their distance to the base station to select cluster-head nodes. However, Improved LEACH causes reduced stability, where the stability period is the duration before the death of the first node. The network stability period is important for applications that require reliable feedback from the network. Thus, we were motivated to investigate the Improved LEACH algorithm and to try to solve the stability problem. A new protocol is proposed in this paper: Stable Improved Low Energy Adaptive Clustering Hierarchy (SILEACH), which was developed to overcome the flaws of the Improved LEACH protocol. SILEACH balances the load between the nodes by utilizing an optimized method that considers the nodes’ distance to the base station and their residual energy to select the cluster-head nodes and considers the nodes’ distance to the cluster head and the base station to form clusters. The simulation results revealed that SILEACH is significantly more efficient than Improved LEACH in terms of stability period and network lifetime.

Task scheduling is critical in heterogeneous systems especially with the huge number of tasks transmitted over grid causing system delay. Since heuristics are proposing methods for solving heterogeneous computing systems, several techniques were proposed for the scheduling on grid computing systems to get better execution time. In this paper, a proposed new heuristic algorithm named Two Stages Tasks Transfer (TSTT) algorithm to enhance Tenacious Penalty Based scheduling (TPB) algorithm. Heterogeneous Computing Scheduling Problem (HCSP) mathematical model has been used, where the independent tasks assigned to heterogeneous machines with different characteristics. Twelve datasets with different heterogeneity level examined using different heuristic algorithms to compare the performance with our proposed algorithm. The proposed algorithm showed its efficiency in term of makespan, resource utilization metrics for set of tasks.