Research experience
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Jan 1997
Research: University of Michigan-Dearborn
University of Michigan-Dearborn · Department of Computer & Information ScienceUSA · Dearborn -
Jan 1995–
Dec 1996Research: University of Denver
University of DenverUSA · Denver
Publications (11) View all
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Article: Optical TDM sorting networks for high-speed switching
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ABSTRACT: The general time-space-time switching problem in telecommunications requires the use of multichannel time slot interchangers. We propose two multichannel time slot sorters which sort N<sup>2</sup> time-division multiplexed (TDM) optical inputs, arranged as N frames with N time slots per frame using O(Nlog<sup>2</sup>N) optical switch elements. The TDM optical inputs are sorted in place without expanding the space-time fabric into a space-division switch. The hardware components used are 2×2 optical switches (LiNbO<sub>3 </sub> directional couplers) and optical delay lines connected in a feedforward fashion. Two space-time variants of the spatial odd-even merge algorithm are used to design the sorters. By maintaining the number of shift-exchange operations invariant at each stage, the proposed sorters use fewer switches than previously proposed sorters using switches with feedback line delays. The use of local control at each 2×2 switch makes the proposed sorters more practical for high-speed optical inputs than Benes-based time slot permuters with global control and high latency, which affects interframe distance. Both time slot sorters support pipelining of input frames and sorted outputs are available at each time slot after an initial frame delay. The proposed sorters find practical application in the time-domain equivalents of space-division, nonblocking, self-routing packet switches using the sort-banyan architecture, such as the Starlite switch, Sunshine switch, etcIEEE Transactions on Communications 07/1997; · 1.68 Impact Factor -
Article: SXmin: a self-routing high-performance ATM packet switch based on group-knockout principle
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ABSTRACT: We propose SXmin: a self-routing, group-knockout principle based asynchronous transfer mode (ATM) packet switch which provides comparable delay-throughput performance and packet loss probabilities at significantly reduced hardware requirements compared to earlier switches. The M×N SXmin consists of an N×N Batcher sorter followed by log<sub>2</sub>N-1 stages of sort-expander (SX) modules arranged in the form of a complete binary tree. Each SX module consists of a column of 2×2 switches with a wraparound-unshuffle input-output interconnection. This enables the hierarchical utilization of the group-knockout principle to expand the number of inputs by a small factor at each stage, resulting in a significant reduction in overall hardware complexity. Routing at each switch is controlled by a single bit. However, in case of contention, a dual bit resolution algorithm is used locally which drops excess packets in a predetermined manner while ensuring global randomness of packet loss over the entire switching network. There are no internal buffers at the individual stages and therefore the internal delay is constant and proportional to the number of stages. The use of simple hardware components and regular interconnections in the SX modules makes the network suitable for optical implementationIEEE Transactions on Communications 07/1997; · 1.68 Impact Factor -
Conference Proceeding: STWnet: a high bandwidth space-time-wavelength multiplexed opticalswitching network
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ABSTRACT: We propose STWnet, a self-routing high bandwidth optical network architecture for interconnecting users, grouped together as g groups with w users per group. STWnet uses the three dimensions of space, time, and wavelength by combining the advantages of space and temporal switching with the benefits of wavelength parallel data transmissions. Technologically difficult switching of individual wavelengths is avoided by prearranging transmissions in a way that they can be switched in a wavelength insensitive manner. Wavelengths are reused within the network thus allowing for a larger switching fabric. The proposed architecture can be internally expanded either in the spatial or temporal dimension to allow for multiple packets to be delivered to the same destination group. The expansion factor is determined based on the group knockout principle and given typical traffic patterns is a small number. STWnet allows easy group to group multicasting and broadcasting while system-wide multicasts and broadcasts can be achieved through repetitive group-to-group transmissions. The network uses readily available components such as opto-electronic directional couplers, fixed wavelength transmitters, and diffraction based parallel receivers while avoiding the use of relatively slow and expensive tunable componentsINFOCOM '97. Sixteenth Annual Joint Conference of the IEEE Computer and Communications Societies. Proceedings IEEE; 05/1997 -
Conference Proceeding: High throughput optical algorithms for the FFT and sorting via datapacking
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ABSTRACT: This paper demonstrates that the potential for very high speed computation provided by optical technology can be achieved for important computational problems including the fast Fourier transform and sorting. First a programming model that captures the `time-of-flight' characteristics of optical fibers and switching elements is presented. Then it is shown that the FFT and the radix sort algorithms can both be reduced to the computational kernel of `packing' intermediate data results that are continuously moving through an optical fiber. New algorithms are developed for the general packing problem, and the details of how to implement them in optics are presented. The resulting systems have the potential for operating at clock rates that are two or more orders of magnitude higher than conventional computersMassively Parallel Processing Using Optical Interconnections, 1996., Proceedings of the Third International Conference on; 11/1996 -
Conference Proceeding: Optical TDM switch architectures with distributed control
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ABSTRACT: We propose an optical TDM switch architecture using O(log<sup>2 </sup> N) 2×2 single-bit controlled optical switching elements for interchanging time slots in a 1× N TDM frame. The distributed single-bit control is obtained on the fly at each switching element. The switch also improves on traditional TDM cross-connect systems by allowing the simultaneous delivery of multiple time slotted packets to a single destinationMilitary Communications Conference, 1996. MILCOM '96, Conference Proceedings, IEEE; 11/1996
