Preamble TDMA Explaination

Here is a mini TDMA Explaination that my wife and I came up while understanding preamble based TDMA for a NS-2 project.

Preamble based TDMA:

1. There are different time slots to send and recv data

2. NS only supports single hop preamble based tdma

3. Each node has a dedicated subslot to broadcast the destination id of the outgoing packet

4. Other nodes listen in the preamble and record the time slot to recv data

5. There is a separate preamble and data transmission phase

Lets us consider 4 nodes where:

Node 1 wants to send data to node 3

Node 2 wants to send data to node 1

Node 3 wants to send data to node 2 and

Node 4 has no data to send

Preamble phase

According to point 3, during the preamble phase each node will put the destination id of the outgoing packet in its dedicated slot in the preamble

According to point 4, each node will record the time slots in which it has to recv data in the preamble phase

Node 1 recorded that it has data to recv in slot 2

Node 2 recorded that it has data to recv in slot 3 and

Node 3 recorded that it has data to recv in slot 1

Data transmission phase

Node 1 will put the data to send in slot 1

Node 2 will put the data to send in slot 2

Node 3 will put the data to send in slot 3

Hence proving point 1 i.e.

Node 1 used slot 1 to send data and slot 2 to recv data

Node 2 used slot 2 to send data and slot 3 to recv data

Node 3 used slot 3 to send data and slot 1 to recv data