ABL-tree: a constant diameter interconnection network for reconfigurable processor arrays capable of distributed communication

An advanced interconnection network called "ABL-tree" is proposed for constructing reconfigurable processing-node arrays with a constant network diameter of t(⩾3) for expanding the size of the array. An ABL-tree can be constructed by using small subarrays of processing nodes interconnected as ring, 2-D toroidal mesh, or the complete connection scheme, whose size is determined by the minimal repetition pitch of a node-coloring pattern with an inter-node distance of t (⩾3) for the base array. The processing nodes of the subarrays are connected to a tree-structured switching network with a height of two according to the node-coloring pattern. Inter-node communication is achieved in a distributed manner by selectively using a node adjacent to the source node in the subarray as a relay node whose color is the same as that of the destination node. The proposed scheme allows reconfiguration of large rings or toroidal meshes with various aspect ratios by selectively arranging the subarrays in a free order. It is advantageous in routing, fault tolerance, and the number of switching elements