CCW08 Becomes an issue when designing algorithms The output of the - - PowerPoint PPT Presentation

Costas Busch Louisiana State University CCW’08

 Becomes an issue when designing algorithms  The output of the algorithms may affect the

energy efficiency

 Computation power at each node is abundant

• Unlimited energy for computations at each node
• Computation time at each node does not affect

total time complexity

 Point to point communication

• Messages in local neighborhood can be sent

simultaneously

• Message delivery dominates time complexity

 The network is reliable

• The network topology does not change
• The messages are delivered as expected

 Global Synchronization

• All nodes can synchronize
• A special node initiates the algorithm

 The algorithm runs only once

• One shot problems

 Computation power is limited  Communication is not point-to-point

• Requires more energy due to channel interference

 The network is unreliable (ad hoc, mobility)

• More energy to transfer messages

 Global synchronization is not easy

• More messages, energy to achieve synchronization

 An algorithm may run forever

• It continuously consumes energy

 Consider energy consumption when

designing algorithms

 Do not make strong assumptions  Design algorithms with:

 Smaller computation at each node  Low message complexity  Self-stabilizing  Local  Online

Classic metrics:

 Number of messages  Total time

New metrics:

 Max, Average utilization of the nodes  Combination of the above metrics

• Number of Messages X Total Time?

 What are realistic metrics of performance?

 Topology Control

• Focuses on obtaining sparse connected spanners,
• But what is the effect on load balancing?

 Routing

• Focuses on just obtaining routing paths,
• But what is the effect on congestion?

 Peer-to-peer

• Focus on uniformly distributing and accessing the

data

• But what about the actual node utilization and

actual network paths?

 Data aggregation

• Focus on minimizing the total aggregation cost,
• But how does this affect the max cost at a node?

 Facility location

• Focus on path distances
• But how about the load on each facility?

 How frequently do uniform disc graphs

appear in practice?

 Can we afford to ignore maximum node

utilization?

 Is the computation power at each node

abundant?