The USC Andrew and Erna Viterbi School of Engineering USC Signal and Image Processing Institute USC Ming Hsieh Department of Electrical Engineering University of Southern California

Technical Report USC-SIPI-284

“Design For a Shared Memory Computer With a Combining Optical Interconnection Network Using External Routing”

by Clare Waterson

May 1995

The design of a fine-grained MIMD computer architecture, the Shared Memory Optical/Electronic Computer (SMOEC), is presented. The SMOEC architecture consists of electronic processing elements and memory modules interconnected with a novel combining passive optical interconnection network which is controlled by a separate electronic routing processor. The hybrid system design emphasizes the strengths of the two technologies, using optics for communication and electronics for processing. Sample system implementation recipes exemplify the flexibility, realizability, and scalability of the SMOEC system architecture. The system-level focus on interrelated development of three main design facets---architecture, hardware, and control algorithms---has been crucial in designing a well-balanced high performance system.

The design of the optical interconnection network, the Free-space Interconnection with Externally-controlled Routing (FIER), is presented in detail. The network is implemented using exclusively passive optical elements, and it employs a shuffle--exchange topology. Each shuffle--exchange stage is optically cascadable. The FIER switch nodes are capable of broadcast and combine operations in additional to bypass and exchange. The FIER is designed to be circuit-switched by an external electronic routing processor. Although the FIER is designed to be used as a subsystem within the SMOEC, it may be used as a subsystem in other communication or computing architectures.

A review of Extended Generalized Shuffle (EGS) network theory is provided to give a solid theoretical background for the interconnection topology employed in the FIER and to prepare for presentation of a new routing algorithm.

A new algorithm, the Flexible Localized Algorithm for EGS-network Management (FLAEM), is presented. This algorithm was developed for circuit-switched combining regular simplified EGS networks (such as the FIER optical network); it parallelizes the routing process in a different way than the previously available method. The effectiveness of the FLAEM is illustrated by simulation results, which show that the algorithm time complexity is logarithmic in system size ($N$). The FLAEM extends the repertoire of routing techniques available for this class of EGS networks.

To download the report in PDF format click here: USC-SIPI-284.pdf (37.3Mb)