1. Mobile Agent Migration Problem Yingyue Xu

2. Energy efficiency requirement of sensor networks Mobile agent computing paradigm Data fusion, distributed processing in sensor networks Motivation

3. Client/Server-based Computing Several clients One server Clients send data to server Server processes these data Drawbacks: Creates heavy network traffic and consumes bandwidth, resulting in poor performance Dependent on the performance of the server

4. A New Paradigm: The Mobile- agent-based Computing Mobile agent is a special kind of software Migrate from node to node, carrying partially integrated results and performing data processing autonomously Data stay at the local site, while the processing task is moved to the data sites.

5. Itinerary –Route of migration Identification –Unique for each mobile agent Data buffer –Carries the partially integrated results Method –Execution code carried with the agent Architecture of Mobile Agent 160.10.30.100 itinerary data buffer method identification

6. Problem Definition The problem of finding an optimal sequence of nodes for a mobile agent to visit in order to complete its task in the minimum expected costs.

7. Background: Travel salesman problem

8. Travel salesman problem o given a finite number of "cities" along with the cost of travel between each pair of them, find the cheapest way of visiting all the cities only one time and returning to your starting point. o NP-complete: computational effort required to solve this problem increases exponentially with the problem size. o Single mobile agent, full connection, single visit problem

9. Background Vehicle routing problem to deliver a set of customers with known demands on minimum-cost vehicle routes originating and terminating at a depot. NP-complete Special case is the Travel Salesman Problem multiple mobile agents, full connection, single visit problem

10. Exact Approaches: propose to compute every possible solution until one of the bests in reached o Branch and bound Heuristics: perform a relatively limited exploration of the search space and typically produce good quality solutions within modest computing times o Constructive methods MetaHeuristics: the emphasis is on performing a deep exploration of the most promising regions of the solution space. o Genetic algorithms o Ant algorithms o Tabu search Solution Techniques

11. Single or multiple mobile agents Single or multiple visits May not be full connection Mobile agent migration

12. Static methods: centralized methods, compute the route in advance of mobile agent migration. o Can get good solutions o Energy inefficient! o Time consuming Dynamic methods: determine the route locally, on the fly. o Suitable for sensor networks o Need to find a way that minimize searching cost, while achieving satisfying solutions Mobile agent migration problem

13. Katsuhiro Moizumi, “Mobile agent planning problem”, Dartmouth College o Information retrieval o Conclusion: sorting the ratios for the sites, (t i +l)/ p i, into increasing order and visiting the sites in that order Related work

14. Qishi Wu, “On computing the route of a mobile agent for data fusion in a distributed sensor network” o Maximizing an objective function, shown to be NP hard o Using genetic algorithm to solve optimization problem o Develop a simulator in VC to simulate o Used in our simulations Related work

15. Once the mobile agent arrives a node, it randomly selects a destination from its neighbors Easier to implement Random selection algorithm

16. Greedy algorithm Once the mobile agent arrives a node, it selects a destination from its neighbors that

17. Using Java Implement random selection, greedy algorithms For optimal path, we use the software from LSU to calculate the path, then simulate in our simulator Simulation

18. Parameters 30m by 30m Grid deployment Transmission range: 30m Target position in the center of the area Accuracy threshold: 0.9

19. Results

21. Greedy algorithm is the best in term of energy consumption and hop number The optimal algorithm may not always return the best solution Conclusions