REAL-TIME COMMUNICATIONS USING TDMA-BASED MULTIACCESS PROTOCOL

In this paper, we study first the performance issues, especially messa ge sojourn time and message overflow, of the TDMA protocol and then sh ow how to use these results to design protocol parameters in order to meet the soft real-time requirements. We consider a single queue with multiple output (b messages) and finite buffer capacity (denoted by K) , K and b being two protocol parameters that a designer can choose. As suming Poisson fixed-length message arrivals, the exact expressions fo r the distribution function of the message sojourn time and the overfl ow probability are derived. It has been shown that these results can b e applied to various particular cases (e.g. the infinite buffer capaci ty case) and therefore appear as a versatile solution for TDMA schemes . Moreover, the monotonicity for the overflow probability is proved, w hich gives us a theoretical base for the dimensioning task. Using the stated results, the design and implementation of real-time protocols b ased on TDMA can be achieved. An example is examined emphasizing the c hoice of the parameters K and b according to time and overflow constra ints. (C) 1997 Elsevier Science B.V.