There are 4 types of broadcast models: flat model, circular multi disk model, multi disk model, and skewed model. The flat model broadcasts data cyclically without considering subscriber numbers. The circular multi disk model repeats blocks proportionally to hierarchy and broadcasts blocks in a cycle. The multi disk model structures broadcast across multiple disks that spin at different rates. The skewed model clusters and organizes more important data together based on access frequency, placing most accessed data on the fastest disks.

1. Broadcast Models

2. There are 4 types of broadcast models :
1.Flat Model
2.Circular Multi Disk Model
3.Multi Disk Model
4.Skewed Model

3. Flat Model
1.The server broadcasts the data as per cyclic requests
without taking into account the number of devices that
subscribe to a particular record.
2.Flat disk has the best expected performance for uniform
page access probabilities.

4. Circular Multi Disk Model
1.Each block of records pushed with a repetition
rate proportional to its hierarchical level
2.Record blocks R0,R1,R2,R3,R0,R1,R2,R3
transmitted in a single broadcast cycle.
3.All record blocks have an equal priority level.

5. Multi Disk Model
1.Here broadcast is structured as multiple disks of varying sizes,
each spinning at various rates.
3.Consider the below example where page A was stored on a single
page disk and that is spinning twice as fast as the second two-page
disk containing pages B and C.

6. Skewed Model
1.In this model subsequent broadcast of more important data
is clustered together.
2.The data items are organized into the disks depending on
their respective frequencies of access.
3.The data items most frequently accessed are placed in the
fastest disk and least accessed in the slowest disk.

7. 4.Expected waiting time for data with less importance is much higher
than that of important data.
5.For skewed access probabilities, non-flat programs are better.