Part 2: Understanding Trade-Offs in SmartMesh IP

Goal

Understand how latency, data rate and energy trade off for one another.

The "Dust Networks SmartMesh Power and Performance Estimator" (http://www.linear.com/docs/42452) is a Excel-based tool which allows you to evaluate the performance of your network, given a set of constraints.

  • Download and open the performance estimator.

    You will find the documentation of the performance estimator at http://cds.linear.com/docs/en/application-note/SmartMesh_IP_Application_Notes.pdf (Section 23.3, p.131).

    In newer versions of Excel, you might have to enable the contents to be able to run the estimator.

  • In the "Estimator" tab, enter parameters corresponding to the setup in your group. What setting did you use?

    Answer 33.2.1:

    number of motes per depth

                                 
    requested service

    reporting interval


    payload size


    path stability


    supply voltage


    temperature


  • What is the resulting estimated performance of your nodes?

    Answer 33.2.2:

    average current consumption at 1 hop

                          

    mean latency at 1 hop


  • Using the "Battery Life" tab, convert the average current consumption figures in the table above into lifetime, for the following batteries:

    Answer 33.2.3:


    CR2032L-91 AATL9530D
    lifetime at 1 hop


    lifetime at 2 hops


  • Change the parameters to match a typical use case for an industrial process monitoring application: 

    number of motes per depth

    40 (1-hop), 30 (2-hop), 20 (3-hop), 10 (4-hop)

    requested service60 seconds

    reporting interval

    60 seconds

    payload size

    10 bytes

    path stability

    75%

    supply voltage

    3.6

    temperature

    40 C

    battery

    TL9530D

  • What is the estimated performance now?

    Answer 33.2.4:

    hop 1

    mean latency


    average current


    battery lifetime


    hop 2

    mean latency


    average current


    battery lifetime


    hop 3

    mean latency


    average current


    battery lifetime


    hop 4

    mean latency


    average current


    battery lifetime


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