Takahiro IIZUKA Kenji FUKUSHIMA Akihiro TANAKA Hideyuki KIKUCHIHARA Masataka MIYAKE Hans J. MATTAUSCH Mitiko MIURA-MATTAUSCH
The trench-gate type high-voltage (HV) MOSFET is one of the variants of HV-MOSFET, typically with its utility segments lying on a larger power consumption domain, compared to planar HV-MOSFETs. In this work, the HiSIM_HV compact model, originally intended for planar LDMOSFETs, was adequately extended to accommodate trench-gate type HV-MOSFETs. The model formulation focuses on a closed-form description of the current path in the highly resistive drift region, specific to the trench-gate HV-MOSFETs. It is verified that the developed compact expression can capture the conductivity in the drift region, which varies with voltage bias and device technology such as trench width. The notable enhancement of current drivability can be accounted for by the electrostatic control exerted by the trench gate within the framework of this model.
In this paper, we develop a novel two-sample test statistic for edge detection in CT image. This test statistic involves the non-parametric estimate of the samples' probability density functions (PDF's) based on the kernel density estimator and the calculation of the mean square error (MSE) distance of the estimated PDF's. In order to extract single-pixel-wide edges, a generic detection scheme cooperated with the non-maximum suppression is also proposed. This new method is applied to a variety of noisy images, and the performance is quantitatively evaluated with edge strength images. The experiments show that the proposed method provides a more effective and robust way of detecting edges in CT image compared with other existing methods.
Ann-Chen CHANG Chih-Chang SHEN
This letter presents an effective direction of arrival (DOA) estimator that is based on the orthogonal projection (OP) technique. When an OP matrix is attained, the proposed estimator, which dispenses with spatial smoothing (SS) preprocessing, can form the maximizing orthogonality for a single snapshot. Since this technique does not need to perform eigen-decomposition while maintaining better DOA estimates, it also has real-time DOA estimation capability. Numerical results are presented to illustrate the efficiency of this method.
HyunMin SEUNG Jong-Dae LEE Chang-Hwan KIM Jea-Gun PARK
In summary, we successfully fabricated the nonvolatile hybrid polymer 4F2 memory-cell. It was based on bistable state, which was observed in PS layer that is containing a Ni nanocrystals capped with NiO tunneling barrier sandwiched by Al electrodes. The current conduction mechanism for polymer memory-cell was demonstrated by fitting the I-V curves. The electrons were charged and discharged on Ni nanocrystals by tunneling through the NiO tunneling barrier. In addition, the memory-cell showed a good and reproducible nonvolatile memory-cell characteristic. Its memory margin is about 1.410. The retention-time is more than 105 seconds and the endurance cycles of program-and-erase is more than 250 cycles. Furthermore, Thefore, polymer memory-cell would be good candidates for nonvolatile 4F2 cross-bar memory-cell.
Joohyun LEE Bontae KOO Hyuckjae LEE
This paper presents a hardware design of high throughput, low latency preamble detector for 3GPP LTE physical random access channel (PRACH) receiver. The presented PRACH receiver uses the pipelined structure to improve the throughput of power delay profile (PDP) generation which is executed multiple times during the preamble detection. In addition, to reduce detection latency, we propose an instantaneous preamble detection method for both restricted and unrestricted set. The proposed preamble detection method can detect all existing preambles directly and instantaneously from PDP output while conducting PDP combining for restricted set. The PDP combining enables the PRACH receiver to detect preambles robustly even in severe Doppler effect or frequency error exist. Using proposed method, the worst case preamble detection latency time can be less than 1 ms with 136 MHz clock and the proposed PRACH receiver can be implemented with approximately 237k equivalent ASIC gates count or occupying 30.2% of xc6vlx130t FPGA device.
Xiaopeng JIAO Jianjun MU Rong SUN
Turbo equalization is an iterative equalization and decoding technique that can achieve impressive performance gains for communication systems. In this letter, we investigate the turbo equalization method for the decoding of the Davey-MacKay (DM) construction over the IDS-AWGN channels, which indicates a cascaded insertion, deletion, substitution (IDS) channel and an additive white Gaussian noise (AWGN) channel. The inner decoder for the DM construction can be seen as an maximum a-posteriori (MAP) detector. It receives the beliefs generated by the outer LDPC decoder when turbo equalization is used. Two decoding schemes with different kinds of inner decoders, namely hard-input inner decoder and soft-input inner decoder, are investigated. Simulation results show that significant performance gains are obtained for both decoders with respect to the insertion/deletion probability at different SNR values.
The noise in digital images acquired by image sensors has complex characteristics due to the variety of noise sources. However, most noise reduction methods assume that an image has additive white Gaussian noise (AWGN) with a constant standard deviation, and thus such methods are not effective for use with image signal processors (ISPs). To efficiently reduce the noise in an ISP, we estimate a unified noise model for an image sensor that can handle shot noise, dark-current noise, and fixed-pattern noise (FPN) together, and then we adaptively reduce the image noise using an adaptive Smallest Univalue Segment Assimilating Nucleus ( SUSAN ) filter based on the unified noise model. Since our noise model is affected only by image sensor gain, the parameters for our noise model do not need to be re-configured depending on the contents of image. Therefore, the proposed noise model is suitable for use in an ISP. Our experimental results indicate that the proposed method reduces image sensor noise efficiently.
Xu ZHOU Kai LU Xiaoping WANG Wenzhe ZHANG Kai ZHANG Xu LI Gen LI
The nondeterminism of message-passing communication brings challenges to program debugging, testing and fault-tolerance. This paper proposes a novel deterministic message-passing implementation (DMPI) for parallel programs in the distributed environment. DMPI is compatible with the standard MPI in user interface, and it guarantees the reproducibility of message with high performance. The basic idea of DMPI is to use logical time to solve message races and control asynchronous transmissions, and thus we could eliminate the nondeterministic behaviors of the existing message-passing mechanism. We apply a buffering strategy to alleviate the performance slowdown caused by mismatch of logical time and physical time. To avoid deadlocks introduced by deterministic mechanisms, we also integrate DMPI with a lightweight deadlock checker to dynamically detect and solve these deadlocks. We have implemented DMPI and evaluated it using NPB benchmarks. The results show that DMPI could guarantee determinism with incurring modest runtime overhead (14% on average).
Ki Sup HONG Sang Hoon LEE Lynn CHOI
Existing MANET routing protocols may not be efficient for mobile sensor networks (MSNs) since they generate too much control traffic by relying on flooding or route maintenance messages. Furthermore, peer-to-peer communication patterns assumed in MANET would exacerbate the traffic around sink nodes in MSNs. In this paper we propose traffic adaptive routing (TAR) for MSNs; it can reduce the control packets by analyzing and predicting the source, volume, and the patterns of both traffic and mobility. Through its analysis and the prediction of mobility, TAR also copes with dynamic topology changes by carrying out a fast route recovery process. Our theoretical analysis shows that TAR can effectively reduce unnecessary control packet flooding by 53% on average when compared to AODV. We implement TAR on NS-2. Our experimental evaluation confirms that TAR can not only improve the network and energy performance for MSNs but also can be a practical routing solution for MANET and WSNs compared to the existing ad hoc routing protocols.
Yun CHEN Xubin CHEN Zhiyuan GUO Xiaoyang ZENG Defeng HUANG
A highly parallel turbo decoder for 3GPP LTE/LTE-Advanced systems is presented. It consists of 32 radix-4 soft-in/soft-out (SISO) decoders. Each SISO decoder is based on the proposed full-parallel sliding window (SW) schedule. Implemented in a 0.13 µm CMOS technology, the proposed design occupies 12.96 mm2 and achieves 1.5 Gb/s while decoding size-6144 blocks with 5.5 iterations. Compared with conventional SW schedule, the throughput is improved by 30–76% with 19.2% area overhead and negligible energy overhead.
Qieshi ZHANG Sei-ichiro KAMATA
This paper presents a novel color descriptor based on the proposed Color Barycenter Hexagon (CBH) model for automatic Road-Sign (RS) detection. In the visual Driver Assistance System (DAS), RS detection is one of the most important factors. The system provides drivers with important information on driving safety. Different color combinations of RS indicate different functionalities; hence a robust color detector should be designed to address color changes in natural surroundings. The CBH model is constructed with barycenter distribution in the created color triangle, which represents RS colors in a more compact way. For detecting RS, the CBH model is used to segment color information at the initial step. Furthermore, a judgment process is applied to verify each RS candidate through the size, aspect ratio, and color ratio. Experimental results show that the proposed method is able to detect RS with robust, accurate performance and is invariant to light and scale in more complex surroundings.
Ryota MIZUTANI Kentaro KOBAYASHI Hiraku OKADA Masaaki KATAYAMA
This paper discusses the reduction of the amount of transmitted information for the efficient use of frequency resources in wireless feedback control systems, and clarify the effect of the reduction of the amount of transmitted information. As a typical example of the underactuated controlled object, a rotary inverted pendulum is considered. We propose a reduction method for state information fed back from the controller to the controlled object. It estimates angle or velocity state from the previous state. In addition, we propose a reduction method that temporally omits less important control information and state information. Numerical examples clarify the effect of the reduction methods on the control quality. And we show that the reduction methods achieve large reduction of the amount of transmitted information with small disadvantage of the control quality.
Min-Chul SUN Sang Wan KIM Garam KIM Hyun Woo KIM Hyungjin KIM Byung-Gook PARK
A novel tunneling field-effect transistor (TFET) featuring the sigma-shape embedded SiGe sources and recessed channel is proposed. The gate facing the source effectively focuses the E-field at the tip of the source and eliminates the gradual turn-on issue of planar TFETs. The fabrication scheme modified from the state-of-the-art 45 nm/32 nm CMOS technology flows provides a unique benefit in the co-integrability and the control of ID-VGS characteristics. The feasibility is verified with TCAD process simulation of the device with 14 nm of the gate dimension. The device simulation shows 5-order change in the drain current with a gate bias change less than 300 mV.
Due to the increasing need for low-power circuits in mobile applications, numerous leakage and performance optimization techniques are being used in modern ICs. In the present paper, we propose a novel transistor-level technique to reduce leakage current while maintaining drive current. By slightly increasing the channel length at the edge of a device that exploits the edge effect, a leakage-optimized transistor can be produced. By using TCAD simulations, we analyze edge-length-biased transistors and then propose the optimal transistor shape for minimizing Ioff with the same or higher Ion current. Results show that by replacing all standard cells with their leakage-optimized counterparts, we can save up to 17% of the leakage in average for a set of benchmark circuits.
Lu ZHAO Qiao-yan WEN Jie ZHANG
The linear complexity of quaternary sequences plays an important role in cryptology. In this paper, the minimal polynomial of a class of quaternary sequences with low autocorrelation constructed by generalized cyclotomic sequences pairs is determined, and the linear complexity of the sequences is also obtained.
Yong Hwi KIM Ka Hyung CHOI Tae Sung YOON Jin Bae PARK
An instrumental variable (IV) based linear estimator is proposed for effective target localization in sensor network by using time-difference-of-arrival (TDOA) measurement. Although some linear estimation approaches have been proposed in much literature, the target localization based on TDOA measurement still has a room for improvement. Therefore, we analyze the estimation errors of existing localization estimators such as the well-known quadratic correction least squares (QCLS) and the robust least squares (RoLS), and demonstrate advantages of the proposition by comparing the estimation errors mathematically and showing localization results through simulation. In addition, a recursive form of the proposition is derived to consider a real time application.
Shunichi TSUNODA Abu Hena Al MUKTADIR Eiji OKI
Smart OSPF (S-OSPF), a load balancing, shortest-path-based routing scheme, was introduced to improve the routing performances of networks running on OSPF assuming that exact traffic demands are known. S-OSPF distributes traffic from a source node to neighbor nodes, and after reaching the neighbor nodes, traffic is routed according to the OSPF protocol. However, in practice, exact traffic demands are difficult to obtain, and the distribution of unequal traffic to multiple neighbor nodes requires complex functionalities at the source. This paper investigates non-split S-OSPF with the hose model, in which only the total amount of traffic that each node injects into the network and the total amount of traffic each node receives from the network are known, for the first time, with the goal of minimizing the network congestion ratio (maximum link utilization over all links). In non-split S-OSPF, traffic from a source node to a destination node is not split over multiple routes, in other words, it goes via only one neighbor node to the destination node. The routing decision with the hose model is formulated as an integer linear programming (ILP) problem. Since the ILP problem is difficult to solve in a practical time, this paper proposes a heuristic algorithm. In the routing decision process, the proposed algorithm gives the highest priority to the node pair that has the highest product of the total amount of injected traffic by one node and total amount of received traffic by the other node in the pair, where both traffic volumes are specified in the hose model, and enables a source node to select the neighbor node that minimizes network congestion ratio for the worst case traffic condition specified by the hose model. The non-split S-OSPF scheme's network congestion ratios are compared with those of the split S-OSPF and classical shortest path routing (SPR) schemes. Numerical results show that the non-split S-OSPF scheme offers lower network congestion ratios than the classical SPR scheme, and achieves network congestion ratios comparable to the split S-OSPF scheme for larger networks. To validate the non-split S-OSPF scheme, using a testbed network experimentally, we develop prototypes of the non-split S-OSPF path computation server and the non-split S-OSPF router. The functionalities of these prototypes are demonstrated in a non-split S-OSPF network.
Yasuki NANAMORI Toshimitsu USHIO
We consider a multi-hop control network where a wireless network is used for transmissions of input and output data between a plant and a computing system. We formulate a co-scheduling problem of sampling of the plant's outputs, execution of control tasks, and the routing of data transmissions in the network. Several constraints on control tasks and data transmission are described by logical formulae. By using a SAT solver, we obtain a scheduling satisfying the constraints. Through simulation, we investigate the relationship between the computation time in the SAT solver and the number of nodes in the network.
A novel and energy-efficient algorithm with Quality-of-Service (QoS) guarantee is proposed for cooperative spectrum sensing (CSS) with soft information fusion and hard information fusion. By weighting the sensing performance and the consumption of system resources in a utility function that is maximized with respect to the number of secondary users (SUs), it is shown that the optimal number of SUs is related to the price of these QoS requirements.
Qingli ZHAO Fangjiong CHEN Sujuan XIONG Gang WEI
Low-complexity joint subcarrier and power allocation is considered. The applied criterion is to minimize the transmission power while satisfying the users' rate requirements. Subcarrier and power allocation are separately applied. Fixed spectrum efficiency is assumed to simplify the subcarrier allocation. We show that under fixed spectrum efficiency, power allocation can be obtained by solving some sets of linear equations. Simulation result shows the effectiveness of the proposed algorithm.