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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. - PowerPoint PPT Presentation
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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
Scheduling of transmission, routing, broadcasting, spatial querying.
Main issue is power saving, and maintaining connected (is “connected” necessary?)
Different Approaches
Topology Management
Power control Hierarchical
One - hop d-hops
Deterministic
(TMPO)
Non-deterministic
(SPAN, Self-organization)
K-connectivity 1-connectivity
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
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 ???
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)
Power Control
Adjusting transmission range of nodes to achieve both connectivity and reduction of energy consumption
RA assignment problem
1. RA: determine RA such that the total cost of power is minimum
2. HRA:determine the minimum RA such that r-homogeneous assignment is connecting
3. KRA:determine the minimum RA such that is connected
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
Span Algorithm
A set of coordinators on for topology maintenance
Coordinator election based on connectivity and node power
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