1. A Survey of Energy-Efficient Scheduling Mechanisms in Sensor Networks Author ： Lan Wang·Yang Xiao(2006) Presented by Yi Cheng Lin

2. Outline Introduction Classification methodology – Design assumptions – Design objectives Energy saving modes of sensors Distributed scheduling mechanisms in non- hierarchical networks Classification

3. Introduction Sensor networks have a variety of application in both military and civil environment These sensors usually operate on limited battery power An important design objective: minimizing energy consumed by sensing and communication to extend the lifetime

4. Design assumptions

5. Design objectives

6. Energy saving modes of sensors

7. Distributed scheduling mechanisms in non-hierarchical networks Random independent scheduling (RIS) – Time is divided into cycles based on time synchronization method – Active with probability p or go to sleep with probability 1-p (p determines the network life) – Sensor deployment strategies Grid, random, uniform, and 2-dimensional Poisson

9. Sponsored sector – Preserving sensing coverage – Off- duty sponsors, sponsored sector – Use neighbor’s location information and sensing range

10. Maximization of sensor network life (MSNL) – K-coverage – Three states: active, idle or vulnerable – Nodes need to broadcast their state and energy level

11. Lightweight deployment-aware scheduling (LDAS) No need location information Each working node has a mechanism to know the number of working nodes in its neighbor

12. Probing environment and adaptive sensing (PEAS) – High-density sensor network in a harsh environment – Conserve energy by separating all the working nodes by a minimum distance of c – Unbalanced energy consumption Optimal geographic density control (OGDC) – Maximize the number of sleeping sensor – Ensure 1-coverage and 1-connectivity – Minimize the overlapping area

13. Coverage configuration protocol (CCP) Maintain K-coverage and K-connectivity Combine CCP and SPAN Three modes: ACTIVE, LISTEN, SLEEP

14. Adaptive self-configuring sensor networks topologies (ASCENT) – Goal: Maintain certain data delivery ratio – Unfair energy consumption

15. Probing environment and collaborating adaptive sleeping (PECAS) – Probe message – Prevent the occurrence of blind spots – Energy saving lower than PEAS

16. Classification based on assumption

17. Classification based on objectives