9. An Ant Colony System for Dynamic Voltage Scaling Problem in Heterogeneous System

Dynamic voltage scaling is an effective energy minimization technique by conjointly changing the supply voltage and the operational frequency during run-time. In this chapter, an improved ant colony system is presented for distributed systems consisting dynamic voltage scalable processing elements. The energy saving can be obtained by using the DVS algorithm on the schedule obtained by the presented scheduling algorithm. The pheromone information of the ants and the heuristic information inspired by the list heuristic rule and energy consumption are combined together to guide the ants search. The parameter value of heuristic is varied from higher value to lower value to lessen its impact on ants search, while the parameter value of pheromone information is increased during the run of ant algorithm. And the elitist solution is discarded if it cannot be improved from generation to generation. By cooperating several generations of artificial ants, the ants search for the path with a minimum energy consumption cost, and the quality of the solution can be improved for minimizing the energy consumption. Experiments are implemented to demonstrate the performance of the algorithm.