  A novel technique is proposed to optimize energy efficiency for wireless
networks based on hierarchical mobile clustering. The new bi-level clustering
technique minimizes mutual interference and energy consumption in large-scale
tracking systems used in large public gatherings such as festivals and sports
events. This technique tracks random movements of a large number people in a
bounded area by using a combination of smart-phone Bluetooth and Wi-Fi
connections. It can be effectively used for monitoring health conditions of
crowd members and providing their locations and movement directions. An integer
linear programming (ILP) model of the problem is formulated to optimize the
formation of clusters in a two-level hierarchical structure. In order to
evaluate the proposed technique, it is compared to the optimum solutions
obtained from the ILP model for both single-level and two-level clustering.
Moreover, a Matlab/Simulink simulation model is developed and used to test the
technique performance under realistic operating conditions. The results
demonstrate a very good performance of the proposed technique.
