Improving the Timed Token Protocol

We present a critical study of "the timed token" real-time communication protocol. This protocol presents a drawback towards asynchronous messages. In fact, if all stations of the network have permanent synchronous and asynchronous messages, only the first station can transmit its asynchronous messages during a limited interval of time. Then, only synchronous messages will be transmitted until at least one station does not use all its synchronous capacity for the transmission of synchronous messages. The regular timed token protocol [7] has been developed to solve this problem. However, it still occurs in the case where the station uses all its synchronous capacity to send synchronous messages. The proposed here, called improved timed token, uses the main key ideas of the two previous ones and permits the transmission of synchronous messages in some critical situations where they cannot be transmitted when using either timed or regular timed token protocols.