1 / 17

Distributed cross-layer scheduling for In-network sensor query processing

Distributed cross-layer scheduling for In-network sensor query processing. PERCOM 2006 2006. 11. 23(THU) Lee Cheol-Ki Network & Security Lab. Contents. Introduction Related work System overview Schedule construction Schedule execution Evaluation Conclusion and future work.

Download Presentation

Distributed cross-layer scheduling for In-network sensor query processing

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Distributed cross-layer scheduling for In-network sensor query processing PERCOM 2006 2006. 11. 23(THU) Lee Cheol-Ki Network & Security Lab.

  2. Contents • Introduction • Related work • System overview • Schedule construction • Schedule execution • Evaluation • Conclusion and future work 컴퓨터 구조 특강

  3. Introduction(1/2) • In-network sensor query processing systems • Data acquisitional applications of wireless sensor networks • Inject queries into the network • The networked sensor nodes work together to process the queries • Send back the query results • Critical issue : To reduce power consumption • Major sources of energy waste • Idle listening, over hearing, collision and control packet overhead • Immediate solution • To make the nodes sleep as much as possible • Focus on tree networks (similar to the existing schemes) 컴퓨터 구조 특강

  4. Introduction(2/2) • Process of systems • A node first checks Applicable Transmission Slots • Sends it to parent • The parent sends the assigned transmission timing • The node arranges it about tasks in all layers • Execution the schedules 컴퓨터 구조 특강

  5. Related work(1/2) • Scheduling has been applied to different layers • TinyDB in query layer • S-MAC in MAC layer • Centralized approach (Florens) • Sink allocate transmission timing to all other nodes in WSN • Sink know the network topology → difficult, high cost • Destributed approach • Flexible Power Scheduling (FPS) • Distributed on-demand power-management protocol for tree networks • Reducing the collision between siblings • But, not reducing the collision between neighbors that are not siblings 컴퓨터 구조 특강

  6. Related work(2/2) • Sichitiu • The source node broadcast a special route setup packet with neighbors • Temporary schedule → permanent schedule (after arriving at sink node) • Frequent collision → dead nodes → inaccurate query result • In this paper • Considering all tasks query injecting, computation, aggregation • Consecutive sleeping and transmission timing to nodes • All layers of a query processing system are involved 컴퓨터 구조 특강

  7. System overview • In-network sensor queryprocessing system • Construct routing tree • Sink inject a query • Nodes construct schedules • Sink broadcasts synch-signal • Bottom-up report to sink • Run following the schedules • Scheduling module • Schedule construction • Time synchronization • Schedule execution <A typical WSN setup> <Architecture of scheduling module> 컴퓨터 구조 특강

  8. Schedule construction(1/4) • Schedule construction module • Constraints for schedule construction <Example of constraint ⅲ> 컴퓨터 구조 특강

  9. Schedule construction(2/4) • Constraints • Focus on collisions at the parent node of a sender • Complete collision-free scheduling → high overhead, impractical • In practical • D and E sends packet simultaneously⇒ Collision occurs in B • But, don’t affect to the query results <An example of the collision> 컴퓨터 구조 특강

  10. Schedule construction(3/4) • Notation • Variables • CTS (Children Transmission Slots), ATS (Applicable Transmission Slots),TSI (Transmission Slot Information), CATS • Type of time slots • PL/R(processing-listening/receiving), Q/M(Query injection/maintenance),Sleeping slots, transmission slots • Procedures • A node, to determine ATS (DetermineApplicableTransmissionSlots) • Sends the packet to the parent • Parent node, CTS for children (AllocateChildrenTransmissionSlots) • A node receive TSI from the parent node • Sends ACK 컴퓨터 구조 특강

  11. Schedule construction(4/4) • Complete schedule • ConstructSchedule arrangesthe time slots for PL/R, Q/M <Example of complete schedules> 컴퓨터 구조 특강

  12. Schedule execution • Execution involves the timing control of all layers • MAC layer checks whether it is time for transmission • Earlier than allocated transmission time • Copy the messages to a memory buffer and wait • Timer setup (automatically transmission) • Waiting time should be shorter than the interval of 2 transmissions • Routing layer • Control the timing of transmission for the route maintenance messages 컴퓨터 구조 특강

  13. Evaluation(1/4) • Scheme comparison (DCS, FPS, SS) • The experimental setup • The same experimental setup as that Sichitiu used • 100 nodes in an 80m*80m rectangular area, Trans-range : 25m • Query processing performance • The experimental setup • 10 Crossbow MICA2 motes, optimized TinyDB, original TinyDB • HP-4156 oscilloscope for measuring the power consumption • VMNet simulator 컴퓨터 구조 특강

  14. Evaluation(2/4) • Scheme comparison • Scheduling overhead • Time of constructing a schedule • Schedule comparison • Number of dead node • Non-scheduled node, conflict-scheduled node • AFS (Average frequency of switching between an active slot and a sleeping slot) <Scheduling overhead> <Average frequency of switching> <Number of dead nodes> 컴퓨터 구조 특강

  15. Evaluation(3/4) • Query processing performance • Schedule for in-network aggregation • VMN : Emulated network in VMNet • Query 1 • SELECT avg(light) FROM sensors • Sample intervals • 2, 10, 60 seconds • Comparison optimized TinyDB with original TinyDB • 42%, 67%, 75% at sample interval of 2s, 10s and 60s <The VMN topology with schedules> 컴퓨터 구조 특강

  16. Evaluation(4/4) • Power consumption improvement • Difference between measurement in VMNet and that in the real WSN within ±15% • Difference in the topologies • Measurement errors of the oscilloscope <Power consumption improvement> 컴퓨터 구조 특강

  17. Conclusion and future work • Propose scheduling scheme for Power efficiency • Reduce the number of dead nodes • Reduce Switching frequency • In-efficient to reconstruct a schedule when • A change in the network topology • A new query arrives 컴퓨터 구조 특강

More Related