Nested threshold cell discarding with dedicated buffers and fuzzy scheduling

This paper deals with overload control in asynchronous transfer mode (ATM) networks via priority cell discarding mechanisms. In the traditional nested threshold cell discarding (NTCD) mechanism a single queue is logically partitioned by a number of non-decreasing threshold levels. The number of threshold levels is equal to the number of traffic classes. Cell discarding depends on the class of a cell and the occupied queue length. As a result, only the highest class of traffic has its dedicated buffer at the tail of the queue. In the proposed mechanism, we allow each class to have a small portion of the dedicated buffer, thus achieving better performance in the cell loss rate for all classes of traffic. Adaptive scheduling using a fuzzy logic technology is also proposed to optimize the cell services sequence and reduce cell losses