Scheduling for a TTCAN network with a stochastic optimization algorithm

The TTCAN protocol is a new development in CAN technology that specifies a time-slot based communication mechanism. TTCAN technology avoids the transmission collisions commonly found in standard CAN networks. In TTCAN, all the message instances are transmitted only on previously allocated time-slots. No other instance may be transmitted on an allocated time-slot, so transmission collisions are avoided. Before transmitting a message set over a TTCAN network, it is necessary to create a valid scheduling table that specifies how the time is discretized into time-slots and how the message instances are allocated into those time-slots. Building a valid optimized scheduling table that follows the TTCAN specification isnÕt trivial. Additionally, several distinct scheduling tables may be built for the same message set, so it is necessary to use some quality criterion to select one among all. Typical message sets include a large number of messages, making manual scheduling a very hard and error-prone process. This means it is desirable to use automated tools that compute a feasible scheduling table automatically for a given message set. In this paper, we present a scheduling tool for TTCAN networks that generates a valid scheduling table using a stochastic optimization algorithm. The tool attempts to optimize the scheduling table so it will generate solutions with low jitter. The tool was applied to two well known message sets used in the automotive industry and results are positive. 1