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Exercise 35: Video bandwidth for access and for backhaul

Please revert to the default WiMAX-DSL02 model for this exercise.

Demand

  1. First of all look at the demand inputs for the Video service. The peak-driven calculation starts with the assumed 5.5Mbit/s bandwidth per connection, and then factors in a contention ratio of 20.0.
  2. Returning to the icon, select Show Dependents from the icon menu. Three other elements are highlighted.

The Video Set-Top Box resource has a simple requirement per connection from the Video service, and in addition there are two dependent transformations.

User data

WiMAX access bandwidth refers to the busy-hour bandwidth defined by the service (in proportion to the number of users), whereas Video backhaul bandwidth refers to a separate calculation in the service user data.

Save the model as WiMAX-DSL35

  1. Experiment with different values for the contention ratio input, and also the number of TV channels defined in User Data.
  2. Return both inputs to their original values (20, 15) before proceeding.

Save and run the model

  1. Draw the graph Transformation Instantaneous Output for both the transformations mentioned above and check that they produce sensible results.

Things that you should have seen and understood

Expression transformation
Demand, User Data, Show Precedents, Transformation Instantaneous Output

 

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