Model Description

This example shows two sources sharing a channel using time-division multiplexing (TDM). In the objects $q_1$ and $q_2$ packets are generated and served if the object has the token. The token stays with $q_1$ or $q_2$ until one of the following two events occurs: (1) a timeout expires (the timeout is the upper bound for the time an object can remain with the token) or (2) the queue is empty. The Channel object manages the token. When there is no packets to serve in the system, the token remains with the Channel object until a packet is generated in $q_1$ or $q_2$.

There are three objects in the model:

Channel

this object sends the token to $q_1$ and $q_2$. If the queues do not have packets, the token remains with the channel.

$q_1$ and $q_2$

these objects have three events:

1. Packet_Arrive: generation of packets at exponentially-distributed intervals;
2. Service: transmission of the first packet in the queue if the object has the token;
3. Timeout: sends the token to the channel.

The model is shown in Figure .

Figure: The Multiplex Channel Model.

The TANGRAM-II description of the queue object is shown in Figure .

Figure: The Queue Object.