In Elastic Lambda Aggregation Network (EλAN), fault recovery using an Optical Line Terminal (OLT) in a different Central Office (CO) is applicable due to virtualization of OLT and active Optical Distribution Network (ODN). In addition, the Time Division Multiple Access (TDMA)-based OLT sharing method has been proposed to maintain minimum connectivity of the excessive number of Optical Network Units (ONU) from a single OLT. In this letter, we report the experiments of these two fault recovery methods implemented on the software-based EλAN prototype system. The required time from failure detection to connection recovery was evaluated in these experiments.
Adaptive clutter suppression (ACS) is a technique that mitigates signals from undesired objects by using subarrays. However, because many of existing wind profiler radars (WPRs) have a single-channel receiver, ACS cannot be applied to them. Aiming at implementing ACS capability to existing WPRs, a pilot system composed of auxiliary subarrays, Universal Software Radio Peripheral (USRP), and a workstation, was developed. The use of USRP enabled multi-channel reception and easy development of the software for real-time data processing by using C++. An example, in which ACS was applied to signals collected by the pilot system, is presented.
A novel all-optical feedback automatic gain control scheme for remote optically pumped amplifiers has been proposed. The static and dynamic gain control characteristics of the remotely pumped erbium-doped fiber amplifier have been experimentally clarified. The maximum gain excursion has been successfully reduced by a factor of ∼10 from 2.1 dB to ∼0.2 dB using the proposed gain control scheme.
This paper describes the implementation and design of interface for peripheral component interconnect express (PCIe) interconnect and memory in a complex system on chips (SoC). PCIe bus traffic is made of a series of PCIe bus transactions. The direction of the data will be from initiator to completer (for write transaction) or vice-versa (for read transaction). The interface will read the command of the master and send corresponding response to the master. The major objective of the project is performance verification of SoC on a dedicated channel between PCIe end point and memory using performance models. We are using direct memory access (DMA) type of requests and bandwidth is measured at bottleneck for different PCIe generations, lane configurations and payloads. Bandwidth obtained is being compared with theoretical peak bandwidth calculated.
This letter proposes to use an ultra-wideband (UWB) radar for drone detection and experimentally investigates feasibility of the proposal. First, the radar cross section (RCS) of a typical quadrotor drone is clarified. Next, radar range profiles of a flying drone are discussed. As a result, we have confirmed that an UWB radar with high range resolution can detect a drone and observed a unique feature of the echoes reflected from the drone’s rotor blades. The feature will enable us to distinguish a drone from other flying objects.
To reduce peak-to-average-power ratio (PAPR) of OFDM signals, a self-synchronized-scrambler-based selected-mapping (SS-SLM) has been investigated, where the transmit sequence is scrambled to reduce PAPR. In this method, the receiver needs to use descrambler to recover the original data. However, the descrambling causes error propagation which degrades bit error rate (BER). In this paper, we propose a partially self-synchronized-scrambler-based selected-mapping (PSS-SLM) which scrambles only most significant bits allocated to I-phase and Q-phase of QAM symbols. Numerical results show that the proposed PSS-SLM achieves better BER than that of SS-SLM in QAM-OFDM systems while keeping the same PAPR reduction capability as SS-SLM.
A circularly polarized (CP) waveguide antenna using L-shaped probe is presented. The proposed antenna can cover the UWB (Ultra Wideband) high-band (34.3%: 7.25 GHz–10.25 GHz in Japan) with 3-dB axial ratio (AR) having a wide range of angle in the radiation patterns. For obtaining this performance, a stepped structure is introduced in the L-shaped probe. The optimization of the stepped structure can control the amplitude ratio of the two orthogonal modes of electric field. This can enhance the AR bandwidth of the previously proposed waveguide antenna using an L-shaped probe and parabolic short wall. Finally, the proposed structure achieves 39% of 3-dB bandwidth keeping a wide angle for radiating CP in an angle of around 135°.
We propose a waveguide to microstrip line transition which perpendicularly connects one waveguide and two microstrip lines. Because the proposed transition consists of only a waveguide and a dielectric substrate, the configuration can be simplified. Additionally the transition does not need via holes on the substrate. This configuration reduces manufacturing complexity and cost. We assume to co-locate the transition and a patch array antenna on the dielectric substrate for millimeter wave automotive radar modules. Because the proposed transition suppress undesired radiation by multi-stage impedance transformers, the desired radiation pattern from the array is not worsen. The small radiation from the transition is shown by simulation. Additionally we fabricate 4 × 4 planar patch array antenna with the proposed transition. Measured and simulated radiation patterns are introduced.
This study proposes a model for estimating the properties of mechanically induced long-period fiber gratings (MLPFGs) based on polarization and applied pressure. The model arises from the linear relation between the applied pressure and coupling coefficients of MLPFGs through utilization of Jones matrix analysis. The transmission property of a fabricated MLPFG can be easily estimated using the relation between the applied pressure and coupling coefficients obtained from the measured spectra of MLPFGs. The estimated spectra around the resonance wavelengths based on our proposed model show good agreement with the measured ones.
The design of transverse electromagnetic (TEM) horn antennas has to consider impedance matching between the feeding point and the aperture. To achieve good impedance matching, several typical tapered transmission lines are applied to the taper shape of TEM horns in this study. The numerical estimation of the antenna characteristic of each TEM horn is performed using the finite integration method. An exponential taper is most applicable to the antenna shape among those transmission line tapers. An exponentially tapered TEM horn, however, has problems in maintaining a single main lobe in the radiation pattern. We propose a shortened exponentially tapered TEM horn in which has a simple structure that improves the radiation directivity, and the estimation results show its effectiveness as a broadband antenna.