Bounded Broadcast in Systolic Arrays

Much work has been done on the problem of synthesizing a processor array from a system of recurrence equations. Some researchers limit communication to nearest neighbors in the array; others use broadcast. In many cases, neither of the above approaches result in an optimal execution time. In this paper a technique called bounded broadcast is explored whereby an element of a processor array can broadcast to a bounded number of other processors. This technique is applied to the problems of transitive closure and all-pairs shortest distance, resulting in time complexities that are smaller than those reported previously. In general, the technique can be used to design bounded broadcast systolic arrays for algorithms whose implementation can benefit from broadcasting.