We designed waveguide crossings using the wavefront matching method to reduce the excess loss of a silica-based optical 8 × 8 matrix switch. We fabricated the switches using silica-based planar lightwave circuit (PLC) technology and confirmed that the excess loss of our designed waveguide crossings was lower than that of conventional crossings by 0.3dB. The average insertion loss of the fabricated switch including fiber-coupling loss was 1.7dB, which is the lowest value yet reported for a PLC-based switch. The designed waveguide crossings are practically useful for improving the performance of PLC switches with a large number of crossings.
One-way delay measurement requires end-to-end hosts to be synchronized in clock time on network. However, there is the relative or absolute difference between two clock times by reason of clock offset, clock skew and so on. In this paper, we present a theorem, methods and simulation results of one-way delay and clock offset estimations between end-to-end hosts. The proposed theorem is a relationship between one-way delay, one-way delay variation and round-trip time, and we show that the estimation error is mathematically smaller than a quarter of round-trip time.
Fuzzy Commitment Scheme is a popular technique for biometric template protection. The idea is to bind an random bit string with a biometric template in binary format called difference vector. Ideally, a difference vector is infeasible to recover either the biometric template or the random bit string without any knowledge of the user's biometric data. Yet, this is only valid if the biometric template is uniformly random, which is not the case in reality. In this paper, we propose a method known as Randomized Dynamic Quantization transformation to binarize biometric data. The transformed bit strings are highly distinctive among the users and near to uniformly random. We demonstrate the implementation in the context of fingerprint biometrics.
In this paper, novel explicit pulse-based flip-flop having dual precharge nodes is presented. Dual precharging can minimize the parasitic capacitance of each precharge node by making output transistors driven separately, resulting in high-speed and low-power operation. The switching speed is further improved by avoiding the use of stacked transistors for driving the output load. Pulse-based nature of the proposed flip-flop also provides a negative setup time and minimizes the effects of clock skew. The proposed flip-flop was designed using a 0.18um CMOS technology, whose comparison results indicate that the flip-flop achieves up to 32% power reduction with 11% speed improvement. They also indicate that the power-delay product is decreased by up to 39% compared to conventional pulse-based flip-flops.
A new code structure for spectral amplitude coding optical code division multiple access system based on Double Weight (DW) code families is proposed. The DW code has a fixed weight of two. Modified Double Weight (MDW) code possesses ideal cross-correlation properties and the weight can be any even number, which is grater than two. The MDW code possesses ideal cross-correlation properties and exists for every natural number n. Using the MDW code compared to the existing codes such as Hadamard and Modified Frequency-Hopping (MFH) codes canprovide a much better performance. This has been demonstrated from the experiment simulation.
Modulated scattering array antenna (MSAA) for MIMO applications is experimentally studied. The MSAA has a multi-antenna structure, but it is composed of only one normal antenna element together with several modulated scattering elements (MSE). The Error Vector Magnitude (EVM) which indicates the MIMO performance is measured in an indoor environment when a 2-element MSAA is used as the MIMO antenna in a 2 × 2 MIMO system. It is demonstrated that 2-stream data link can be established. However, the EVMs of the 2 streams are quite different and an averaged 7dB difference is observed due to the gain degradation of the MSE, indicating the MSAA can be used in the MIMO applications where simplifying the configuration of MIMO antenna system is taken high priority.
In this paper, we propose a low complexity pipeline FFT processor for MIMO-OFDM systems with four transmitting and four receiving (4 × 4) antennas. The proposed FFT processor is based on multi-channel structure which enables to support multiple data streams efficiently. With mixed-radix algorithm, the number of non-trivial multiplications of the proposed FFT processor are decreased. Implementation results show that the proposed FFT processor reduces the required number of logic gates by 25% over the conventional 4-channel R4MDC FFT processor which has been considered to be the most area-efficient FFT processor for 4 × 4 MIMO-OFDM systems.
Today, real-time applications with critical constraints are usually run in an environment with Real-Time Operating System (RTOS). Services provided by RTOSs are severely exposed to faults which affect both functional and timing of the tasks running on the RTOS based system. In this paper, we introduce a new architecture for RTOS provides more robust services in term of Soft Errors (SEs). We evaluate and analyze robustness of the services due to SEs in two architectures, i.e. SW-RTOS and HW/SW-RTOS. Experimental results show more robust services were provided by HW/SW-RTOS versus purely SW-RTOS regarding SEs.