Time-space-wavelength networks for low-complexity processor interconnection

The authors study a flexible hierarchic design approach of large processor networks with distributed media access. The cluster-based interconnection combines passive metal buses and passive optical star couplers at two hierarchic levels, independently employing interleaved TDMA for conflict-free interprocessor communication. The system delay analysis highlights the tradeoffs of arbitrarily combining space-division at the local level, wavelength-division at the global level, with time-division as a conflict-free access scheme at both levels and in the form of a speedup factor associated with optical transmission. The frame synchronization time that dominates the access delay in TDMA-based protocols is broken down into two additive rather than multiplicative factors. The authors propose a simple distributed slot synchronization scheme that does not require a centralized system clock. It is shown that this hierarchic approach has the advantages of modularity, expansion flexibility, complexity and performance-wise scalability, and spatial bandwidth re-use