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Assignment of Vertical-Links to Routers in Vertically-Partially-Connected 3-D-NoCs

Auteur(s) : S. Foroutan, H. Sheibanyrad, F. Pétrot

Journal : IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems

Volume : 33

Issue : 8

Pages : 1208-1218

Doi : 10.1109/TCAD.2014.2323219

This paper addresses elevator assignment in vertically-partially-connected 3-D-networks-on-chip (NoCs). Elevators are vertical links between dies. Because of yield issues, Through-Silicon-Via (TSV) cost, and heterogeneity in dimension, topology, and technology of different dies, vertically-partially-connected topologies seem unavoidable in the emerging 3-D-NoCs as opposed to fully-connected topologies. In such partially-connected topologies, as there are fewer elevators than routers, the assignment of elevators to routers becomes a new 3-D-specific optimization problem. An improper assignment can lead to dramatic network performance degradation. This paper proposes an elevator assignment method for best-effort wormhole 3-D-NoCs to improve the average network performance. Experimental results show an improvement of about 90% even compared to a greedy (intrinsically good) initial assignment.