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SGF: A State-Free Gradient-Based Forwarding Protocol for Wireless Sensor Network

SGF: A State-Free Gradient-Based Forwarding Protocol for Wireless Sensor Network. Pei Huang, Xi Yang, Yongdong Tan Southwest Jiaotong University Presented by Ming-Tsung Hsu. Outline. Introduction Related Work The SGF Protocol Simulation Results Conclusion. Introduction.

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SGF: A State-Free Gradient-Based Forwarding Protocol for Wireless Sensor Network

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  1. SGF: A State-Free Gradient-Based Forwarding Protocol for Wireless Sensor Network Pei Huang, Xi Yang, Yongdong Tan Southwest Jiaotong University Presented by Ming-Tsung Hsu

  2. Outline • Introduction • Related Work • The SGF Protocol • Simulation Results • Conclusion OPLab@im.ntu.edu.tw

  3. Introduction Types of routing protocols • Table-Driven • Maintenance cost for topology changing • On-Demand • MANET • Scalability and robustness • Position-Based • State-free • GPS for geographic information • Gradient-Based • State-free • Low-cost OPLab@im.ntu.edu.tw

  4. Introduction (cont’d) • State-free Gradient-Based Forwarding (SGF) protocol • sink broadcasts an ADV message to set up the cost field • Source node broadcasts an Open RTS (ORTS) • Neighbors whose cost is smaller than that of the sender will participate in the competition for becoming the next hop • The best one will first respond to the sender with Competing CTS (CCTS) OPLab@im.ntu.edu.tw

  5. Related Work • Position-Based • Beacon-based • the sender must have its own position, the position of its all neighbors (through beaconing) • Dynamic Forwarding Delay • Gradient-Based • “Gradient” means a direction state, set towards the neighboring nodes through which a destined sink is reached • GRAB (GRAdient Broadcast) uses the energy cost as the gradient OPLab@im.ntu.edu.tw

  6. GRAB OPLab@im.ntu.edu.tw

  7. GRAB (cont’d) Fraction of Credit still available “Normalized” distance OPLab@im.ntu.edu.tw

  8. The SGF Protocol • Cost Field Concept • State-Free Minimum-Cost Unicast • Setting Dynamic Response Wait Timer • Recovery OPLab@im.ntu.edu.tw

  9. Cost Field Concept • Cost Field • The minimum energy overhead needed to forward a packet from itself to the sink along the optimal path • Each node sets its cost to the sink as ∞ • Sink broadcasts an ADV message containing its own cost of 0 • Upon hearing an ADV message from node N, node M has a path with cost LN + CN,M • LN is the cost of node N, and CN,M is the cost form N to M • If the new cost is smaller than its current cost LM, • LM = LN +CN,M • Broadcasts an ADV message with its new cost OPLab@im.ntu.edu.tw

  10. Cost Field Concept (cont’d) OPLab@im.ntu.edu.tw

  11. State-Free Minimum-Cost Unicast • An ORTS is broadcasted by the node M • Carries the minimum cost of the node to the sink • Neighboring node • sets a CCTS Response timer only if the cost at this node is smaller than that of the sender • The node (R) that assigns the shortest time value will first respond with Competing CTS (CCTS) • Other neighbors sensing the signal will cancel their timers K R P Sink S M N OPLab@im.ntu.edu.tw

  12. State-Free Minimum-Cost Unicast (cont’d) • After received a valid CCTS, the sender M will extract the responder cost from the CCTS and reset its cost • Subsequent packets (DATA, ACK) are in accordance with 802.11 DCF semantics (DATAACK) K R P Sink S M N Update LM OPLab@im.ntu.edu.tw

  13. Setting Dynamic Response Wait Timer WC,WE, WR are used to tune the weight of each parameter (In simulations, they are assigned 0.5, 0.4 and 0.1 respectively) CMax denote the maximum cost of a single hop OPLab@im.ntu.edu.tw

  14. Setting Dynamic Response Wait Timer (cont’d) • The transmission power? • Time out? • 802.11? (Data, Ack)? OPLab@im.ntu.edu.tw

  15. Recovery - Retreat Mechanism • N has received data from M • N's ORTS timer expired if no response is received • Retransmit ORTS seven times • The node sets its cost to infinity and goes to sleep • M will try to relay it because its local ID matches the value of lastID contained in the message header • If M cannot find another next hop • Request all nodes whose minimum costs are derived from it to explore their new next hop • goes to sleep • The process will be performed till an upriver node (say S) finds a next hop (maybe K). ORTS 7 times K P Sink S M N M Counting? OPLab@im.ntu.edu.tw

  16. Simulation Results -Settings • ns-2 • Single source node and Single sink • 1000x1000m • 512 bytes per 10 seconds OPLab@im.ntu.edu.tw

  17. Success Ratio Collision ADV OPLab@im.ntu.edu.tw

  18. Impact of Node Failures OPLab@im.ntu.edu.tw

  19. Energy Efficiency Comparison OPLab@im.ntu.edu.tw

  20. Conclusion • State-free without geographic information OPLab@im.ntu.edu.tw

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