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Topology Management

Topology Management. Weihang Jiang Weili lin Vishvesh Sahasrabudhe. Outline. The function of “topology management” Different approaches for topology managements Several criteria of a “good” topology management “Problems” will be addressed now and then. The function of topology.

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Topology Management

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  1. Topology Management Weihang Jiang Weili lin Vishvesh Sahasrabudhe

  2. Outline • The function of “topology management” • Different approaches for topology managements • Several criteria of a “good” topology management • “Problems” will be addressed now and then

  3. The function of topology • Scheduling of transmission, routing, broadcasting, spatial querying. • Main issue is power saving, and maintaining connected (is “connected” necessary?)

  4. Different Approaches Topology Management Power control Hierarchical K-connectivity 1-connectivity One - hop d-hops Non-deterministic (SPAN, Self-organization) Deterministic (TMPO)

  5. Several criteria of a “good” topology management • The most important criterion is power saving • Fewer cluster heads • Load balance • Average degree (power control) • Other criterion • Connectivity (SPAN, K-connectivity) • Algorithm convergence speed (self-organization) • Stability (fewer nodes changing their role: delay changes, how to decide the cycle?) • Mobility (always think about how to deal with the impact of movement, can we take advantage of it?) • Fault tolerant

  6. Fewer cluster heads • Method 1, select a lot of cluster heads to let all cluster heads connected, then withdraw unnecessary cluster heads to hosts • Method 2, select minimum dominating set, then add gateways/doorways to connect them • Method 3, using greedy algorithm, then on each phase, the cluster heads are connected • Method 4 ???

  7. Load balance • Method 1, Force long-term working cluster heads back to host nodes and sleep • Method 2, Select cluster heads basing on battery level (maybe partially)

  8. Power Control • Adjusting transmission range of nodes to achieve both connectivity and reduction of energy consumption

  9. 1-connectivity

  10. RA assignment problem • RA: determine RA such that the total cost of power is minimum • HRA:determine the minimum RA such that r-homogeneous assignment is connecting • KRA:determine the minimum RA such that is connected

  11. Problem? • Directional links B B A A

  12. Distance estimation • RSSi: radio signal strength(poor accuracy) • Toa: time of arrival

  13. Preferred K

  14. Mobility • Rely on volatile information(e.g. distance)

  15. K-connectivity • Motivation: fault tolerant

  16. Theoretical background

  17. Main problems

  18. Interesting problems • Relationship between k-connectivity and k minimum degree

  19. Power Management using Span • Requirements of power-saving coordination algorithm • Max idle nodes • Minimal delay in packet forwarding • Non-interference of original paths • No assumption of link-layer’s facilities for sleeping • Interoperate correctly with routing system

  20. Span Algorithm • A set of coordinators on for topology maintenance • Coordinator election based on connectivity and node power

  21. Span Algorithm • Local Coordinator election • Based on Coordinator eligibility • Two neighbors cannot reach each other – node becomes a coordinator • Announcement Contention resolved by back-off delay

  22. Span Algorithm • Delay Calculation based on connectivity and available power • Leads to efficient management of power and approx. maximum connectivity with minimum nodes

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