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A Real-Time Communication Architecture for Wireless Sensor Networks Neil Tang 4/22/2009

A Real-Time Communication Architecture for Wireless Sensor Networks Neil Tang 4/22/2009. Please complete the online course survey at: www.cs.montana.edu/survey. 2. CS541 Advanced Networking. Outline. Reference System Model Design Goals RAP Simulation Results. 3.

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A Real-Time Communication Architecture for Wireless Sensor Networks Neil Tang 4/22/2009

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  1. A Real-Time Communication Architecturefor Wireless Sensor Networks Neil Tang4/22/2009 CS541 Advanced Networking

  2. Please complete the online course survey at: www.cs.montana.edu/survey 2 CS541 Advanced Networking CS541 Advanced Networking

  3. Outline Reference System Model Design Goals RAP Simulation Results 3 CS541 Advanced Networking CS541 Advanced Networking

  4. Reference • C. Lu, B. Blum, T. F. Abdelzaher, J. A Stankovic and T. He, RAP: a real-time communication architecture for large size wireless sensor networks IEEE RTAS’2002, pp. 55-66. CS541 Advanced Networking

  5. System Model • Large scale and high density network • Very limited energy • Queries are usually associated with timing requirements • Data aggregation • Multihop communication • Addressing based on locations • Congestion in “hot regions” CS541 Advanced Networking

  6. Design Goals • Provide general service APIs. • Maximize the number of packets meeting their end-to-end deadlines. • Scale well with a large number of nodes and hops. • Introduce minimum communication and processing overhead. CS541 Advanced Networking

  7. RAP Architecture CS541 Advanced Networking

  8. Query/Event Service API • query(attribute_list, area, timing_constraints, querier_loc) • register_event(event, area, query) CS541 Advanced Networking

  9. Location-Addressed Protocol • Similar to UDP except that messages are addressed by location instead of IP address. • Support three kinds of communications: unicast, area multicast and area anycast. CS541 Advanced Networking

  10. Geographic Forwarding (GF) • GF makes a greedy decision to forward a packet to a neighbor if 1) it has the shortest geographic distance to the packet’s destination among all immediate neighbors; and 2) it is closer to the destination than the forwarding node. • When such nodes do not exist, the GPSR protocol [16] can be used to route packets around the perimeter of the void region. CS541 Advanced Networking

  11. Velocity Monotonic Scheduling • Deadline-aware • Distance-aware CS541 Advanced Networking

  12. Velocity Monotonic Scheduling • Static Velocity Monotonic: • Dynamic Velocity Monotonic: • No synchronization is needed to determine the elapsed time. CS541 Advanced Networking

  13. Priority Queue • Single FCFS Queue: Packets need to be inserted in the order of their priorities. • Multiple FIFO Queues: Each queue corresponds to a fixed priority level. Each priority level corresponds to a range of requested velocities. • Time complexities? CS541 Advanced Networking

  14. MAC Layer Prioritization • Enhanced 802.11 DCF (EDCF) • DIFS: DIFS = BASE_DIFS * PRIORITY • Backoff increase function: CW=CW*(2+(PRIORITY-1)/MAX_PRIORITY) CS541 Advanced Networking

  15. Summary • RAP provides general query and event service APIs. • RAP increases the number of packets meeting their end-to-end deadlines by prioritizing the transmission of contending packets based on their requested velocities. • RAP scales well in large-scale sensor networks since every algorithm/protocol only needs local information. CS541 Advanced Networking

  16. Simulation Settings • Radio transmission range: 30.5m • Packet size: 32-160B • Link bandwidth: 200kbps CS541 Advanced Networking

  17. Simulation Results CS541 Advanced Networking

  18. Simulation Results CS541 Advanced Networking

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