# Communication Networks: Stop and Wait state machine and timing of state transitions

1. Oct 2, 2011

### VinnyCee

1. The problem statement, all variables and given/known data

Consider the operation of a Stop and Wait DLC system as shown below. The system is using 2-bit sequence numbers.

[PLAIN]http://img210.imageshack.us/img210/4496/hw2problem3diagram.jpg [Broken]

<a> Show the state machine from initial state (SN = 00, RN = 00) to the state (SN = 11, RN = 11).

<b> Show the timing of each state transition in the state machine.

2. Relevant equations

None to speak of really.

3. The attempt at a solution

<a>

[PLAIN]http://img262.imageshack.us/img262/1881/2bitstopandwaitstatemac.jpg [Broken]

Does that look right?

<b>

I have no idea. There are duplicate times $t_9$ and $t_{11}$ - is that an error?

Maybe it's just a list (or table) of what state the machine (i.e. - SN = 01, RN = 10... etc.) is at each time t such that $t_0\,\le\,t\,\le\,t_{13}$?

The duplicate times $t_9$ and $t_{11}$ are errors. Ignore the first of each since they don't really change the state of the machine anyways.