Optimal Power Efficient Photonic SWMR Buses

In this paper we solve the problem of minimizingthe power consumption in SWMR (single writer, multi reader)optical buses for both the ring and tree based configurations. Tominimize the power consumption it is necessary to design thebeam splitters in a SWMR bus optimally. A prior approach byBinzhang et al. [5] proposes to use an exponential time NLPbased solution for solving a related problem, and there are otherapproaches for solving this problem sub-optimally. In comparisonwe propose an optimal linear time algorithm for both ring andtree based buses. Additionally, we take into account the factthat the power loss in a splitter is dependent on the split ratio.Subsequently, we propose a hardware version of our algorithmthat takes 4 cycles for a 64-station ring, and 32 cycles for a 64-station balanced tree to compute an optimal configuration. Withthe help of exhaustive Synopsys RSoft simulations, we show thatour SWMR bus is 87% more power efficient than a popularlyused alternative approach proposed by Kurian et al. [9]. Forlarge number of stations, an optimally designed tree based busis a further 25% more power efficient than a ring.