In this paper, two-stage BP detection is proposed for overloaded MIMO. The proposal combines BP with the MMSE pre-cancellation algorithm followed by normal BP detection. In overloaded MIMO systems, the loops in a factor graph degrade the demodulation performance of BP detection. MMSE pre-cancellation reduces the number of connections or coefficient values in the factor graph which improves the convergence characteristics of posteriori probabilities. Numerical results obtained through computer simulation show that the BERs of the proposed two-stage BP detection outperforms the conventional BP with MMSE pre-cancellation in a low bit energy range when the MMSE block size is four and the number of MMSE blocks is one. When the pre-cancellation is applied for complexity reduction, the proposed scheme reduces multiplication operations and summation operations by the same factor of 0.7 though the amount of the performance improvement to the conventional scheme is limited.

In-band full-duplex (IBFD) has been an attractive technology, which can theoretically double the spectral efficiency. However, when performing IBFD in the dynamic-duplex cellular (DDC) system, inter-user interference (IUI) deteriorates transmission performance in downlink (DL) communication and limits IBFD-applicable area and IBFD application ratio. In this paper, to expand the IBFD-applicable area and improve the IBFD application ratio, we propose an IUI reduction scheme using successive interference cancellation (SIC) for the DDC system. SIC can utilize the power difference and reduce the signal with the higher power. The effectiveness of the proposed scheme is evaluated by the computer simulation. The IUI reducing effect on the IBFD-inapplicable area is confirmed when the received power of the IUI is stronger than that of the desired signal at the user equipment for DL (DL-UE). The IBFD-inapplicable area within 95m from the DL-UE, where the IBFD does not work without the proposed scheme, can reduce by 43.6% from 52.8% to 9.2% by applying the proposed scheme. Moreover, the IBFD application ratio can improve by 24.6% from 69.5% to 94.1%.

The Canonical Polyadic Decomposition (CPD) is the tensor analog of the Singular Value Decomposition (SVD) for a matrix and has many data science applications including signal processing and machine learning. For the CPD, the Alternating Least Squares (ALS) algorithm has been used extensively. Although the ALS algorithm is simple, it is sensitive to a noise of a data tensor in the applications. In this paper, we propose a novel strategy to realize the noise suppression for the CPD. The proposed strategy is decomposed into two steps: (Step 1) denoising the given tensor and (Step 2) solving the exact CPD of the denoised tensor. Step 1 can be realized by solving a structured low-rank approximation with the Douglas-Rachford splitting algorithm and then Step 2 can be realized by solving the simultaneous diagonalization of a matrix tuple constructed by the denoised tensor with the DODO method. Numerical experiments show that the proposed algorithm works well even in typical cases where the ALS algorithm suffers from the so-called bottleneck/swamp effect.

This paper proposes a new class of signature codes for synchronous optical code-division multiple access (CDMA) and describes a general method for construction of the codes. The proposed codes can be obtained from generalized modified prime sequence codes (GMPSCs) based on extension fields GF(q), where q=pm, p is a prime number, and m is a positive integer. It has been reported that optical CDMA systems using GMPSCs remove not only multi-user interference but also optical interference (e.g., background light) with a constant intensity during a slot of length q2. Recently, the authors have reported that optical CDMA systems using GMPSCs also remove optical interference with intensity varying by blocks with a length of q. The proposed codes, referred to as p-chip codes in general and chip-pair codes in particular for the case of p=2, have the property of removing interference light with an intensity varying by shorter blocks with a length of p without requiring additional equipment. The present paper also investigates the algebraic properties and applications of the proposed codes.

Any Internet-connected device is vulnerable to being hacked and misused. Hackers can find vulnerable IoT devices, infect malicious codes, build massive IoT botnets, and remotely control IoT devices through C&C servers. Many studies have been attempted to apply various security features on IoT devices to prevent IoT devices from being exploited by attackers. However, unlike high-performance PCs, IoT devices are lightweight, low-power, and low-cost devices and have limitations on performance of processing and memory, making it difficult to install heavy security functions. Instead of access to applying security functions on IoT devices, Internet-wide scanning (e.g., Shodan) studies have been attempted to quickly discover and take security measures massive IoT devices with weak security. Over the Internet, scanning studies remotely also exist realistic limitations such as low accuracy in analyzing security vulnerabilities due to a lack of device information or filtered by network security devices. In this paper, we propose a system for remotely collecting information from Internet-connected devices and using scanning techniques to identify and manage vulnerability information from IoT devices. The proposed system improves the open-source Zmap engine to solve a realistic problem when attempting to scan through real Internet. As a result, performance measurements show equal or superior results compared to previous Shodan, Zmap-based scanning.

In general, since the in-band noise of phase-locked loops (PLLs) is mainly caused by charge pumps (CPs), large-size transistors that occupy a large area are used to improve in-band noise of CPs. With the high demand for low phase noise in recent high-performance communication systems, the issue of the trade-off between occupied area and noise in conventional CPs has become significant. A noise-canceling CP circuit is presented in this paper to mitigate the trade-off between occupied area and noise. The proposed CP can achieve lower noise performance than conventional CPs by performing additional noise cancelation. According to the simulation results, the proposed CP can reduce the current noise to 57% with the same occupied area, or can reduce the occupied area to 22% compared with that of the conventional CPs at the same noise performance. We fabricated a prototype of the proposed CP embedded in a 28-GHz LC-PLL using a 16-nm FinFET process, and 1.2-dB improvement in single sideband integrated phase noise is achieved.

In order to upgrade the refresh rate about High-Resolution (1280×1024) OLED-on-Silicon (OLEDoS) microdisplay, this paper discusses one compression scan strategy by reducing scan time redundancy. This scan strategy firstly compresses the low-bit gray level scan serial as one unit; second, the scan unit is embedded into the high-bit gray level serial and new scan sequence is generated. Furthermore, micro-display platform is designed to verify the scan strategy performance. The experiment shows that this scan strategy can deal with 144Hz refresh rate, which is obviously faster than the traditional scan strategy.

This paper proposes time division multiplexing (TDM) based reference signal (RS) multiplexing for faster-than-Nyquist (FTN) signaling using orthogonal frequency division multiplexing (OFDM). We also propose a subframe structure in which a cyclic prefix (CP) is appended to only the TDM based RS block and the first FTN symbol to achieve accurate estimation of the channel response in a multipath fading channel with low CP overhead. Computer simulation results show that the loss in the required average received SNR satisfying the average block error rate (BLER) of 10-2 using the proposed TDM based RS multiplexing from that with ideal channel estimation is suppressed to within approximately 1.2dB and 1.7dB for QPSK and 16QAM, respectively. This is compared to when the improvement ratio of the spectral efficiency from CP-OFDM is 1.31 with the rate-1/2 turbo code. We conclude that the TDM based RS multiplexing with the associated CP multiplexing is effective in achieving accurate channel estimation for FTN signaling using OFDM.

Feature detection and matching procedure require most of processing time in image matching where the time dramatically increases according to the number of feature points. The number of features is needed to be controlled for specific applications because of their processing time. This paper proposes a feature detection method based on significancy of local features. The feature significancy is computed for all pixels and higher significant features are chosen considering spatial distribution. The method contributes to reduce the number of features in order to match two images with maintaining high matching accuracy. It was shown that this approach was faster about two times in average processing time than FAST detector for natural scene images in the experiments.

Distributed detection techniques of multiple-input multiple-output (MIMO) spatially multiplexed signals are studied in this paper. This system considered employs multiple mobile stations (MSs) to receive signals from a base station, and then share their received signal waveforms with collaborating MSs. In order to reduce the amount of traffic over the collaborating wireless links, distributed detection techniques are proposed, in which multiple MSs are in charge of detection by making use of both the shared signal waveforms and its own received waveform. Selection combining schemes of detected bit sequences are studied to finalize the decisions. Residual error coefficients in iterative MIMO equalization and detection are utilized in this selection. The error-ratio performance is elucidated not only by computer simulations, but also by offline processing using experimental signals recorded in a measurement campaign.

Loading test vectors and unloading test responses in shift mode during scan testing cause many scan flip-flops to switch simultaneously. The resulting shift switching activity around scan flip-flops can cause excessive local IR-drop that can change the states of some scan flip-flops, leading to test data corruption. A common approach solving this problem is partial-shift, in which multiple scan chains are formed and only one group of the scan chains is shifted at a time. However, previous methods based on this approach use random grouping, which may reduce global shift switching activity, but may not be optimized to reduce local shift switching activity, resulting in remaining high risk of test data corruption even when partial-shift is applied. This paper proposes novel algorithms (one optimal and one heuristic) to group scan chains, focusing on reducing local shift switching activity around scan flip-flops, thus reducing the risk of test data corruption. Experimental results on all large ITC'99 benchmark circuits demonstrate the effectiveness of the proposed optimal and heuristic algorithms as well as the scalability of the heuristic algorithm.

This paper proposes a parallel peak cancellation (PC) process for the computational complexity-efficient algorithm called PC with a channel-null constraint (PCCNC) in the adaptive peak-to-average power ratio (PAPR) reduction method using the null space in a multiple-input multiple-output (MIMO) channel for MIMO-orthogonal frequency division multiplexing (OFDM) signals. By simultaneously adding multiple PC signals to the time-domain transmission signal vector, the required number of iterations of the iterative algorithm is effectively reduced along with the PAPR. We implement a constraint in which the PC signal is transmitted only to the null space in the MIMO channel by beamforming (BF). By doing so the data streams do not experience interference from the PC signal on the receiver side. Since the fast Fourier transform (FFT) and inverse FFT (IFFT) operations at each iteration are not required unlike the previous algorithm and thanks to the newly introduced parallel processing approach, the enhanced PCCNC algorithm reduces the required total computational complexity and number of iterations compared to the previous algorithms while achieving the same throughput-vs.-PAPR performance.

In this paper, we propose a model of a diversity receiver which uses an antenna whose antenna pattern can periodically change. We also propose a minimum mean square error (MMSE) based interference cancellation method of the receiver which, in principle, can suffer from the interference in neighboring frequency bands. Since the antenna pattern changes according to the sum of sinusoidal waveforms with different frequencies, the received signals are received at the carrier frequency and the frequencies shifted from the carrier frequency by the frequency of the sinusoidal waveforms. The proposed diversity scheme combines the components in the frequency domain to maximize the signal-to-noise power ratio (SNR) and to maximize the diversity gain. We confirm that the bit error rate (BER) of the proposed receiver can be improved by increase in the number of arrival paths resulting in obtaining path diversity gain. We also confirm that the proposed MMSE based interference canceller works well when interference signals exist and achieves better BER performances than the conventional diversity receiver with maximum ratio combining.

The authors have been investigating the deterioration process of Au-plated slip-ring and Ag-Pd brush system with lubricant to realize stable and long lifetime. Through the past tests, it can be made clear that lubricant is very important for long lifetime, and a simple model of the deterioration process was proposed. However, it is still an issue how the lubricant is deteriorated and also what the relation between lubricant deterioration and contact voltage behavior is. In this paper, the contact voltage waveforms were regularly recorded during the test, and analyzed to obtain the time change of peak voltage and standard deviation during one rotation. Based on these results, it is discussed what happens at the interface between ring and brush with the lubricant. And the following results are made clear. The fluctuation of voltage waveforms, especially peaks of pulse-like fluctuation more easily occurs for minus rings than for plus rings. Further, peak values of the pulse-like fluctuation rapidly decreases and disappear at lower rotation speed as mentioned in the previous works. In addition, each peaks of the pulse-like fluctuation is identified at each position of the ring periphery. From these results, it can be assumed that lubricant film exists between brush and ring surface and electric conduction is realized by tunnel effect. In other words, it can be made clear that the fluctuation would be caused by the lubricant layer, not only by the ring surface. Finally, an electric conduction model is proposed and the above results can be explained by this model.

In the design of electrical contacts, it is required to pursue a solution which satisfies simultaneously multi-objective (electrical, mechanical, and thermal) performances including conflicting requirements. Preference Set-Based Design (PSD) has been proposed as practical procedure of the fuzzy set-based design method. This brief paper newly attempts to propose a concurrent design method by PSD to electrical contact, specifically a design of a shape of cantilever in relay contacts. In order to reduce the calculation (and/or experimental) cost, this paper newly attempt to apply Design of Experiments (DoE) for meta-modeling to PSD. The number of the calculation for the meta-modeling can be reduced to $rac{1}{729}$ by using DoE. The design parameters (width and length) of a cantilever for drive an electrical contact, which satisfy required performance (target deflection), are obtained in ranges successfully by PSD. The validity of the design parameters is demonstrated by numerical modeling.

We propose a novel non-orthogonal multiple access (NOMA)-based optimal multiplexing method for multiple downlink service channels to maximize the integrated system throughput. In the fifth generation (5G) mobile communication system, the support of various wireless communication services such as massive machine-type communications (mMTC), ultra-reliable low latency communications (URLLC), and enhanced mobile broadband (eMBB) is expected. These services will serve different numbers of terminals and have different requirements regarding the spectrum efficiency and fairness among terminals. Furthermore, different operators may have different policies regarding the overall spectrum efficiency and fairness among services. Therefore, efficient radio resource allocation is essential during the multiplexing of multiple downlink service channels considering these requirements. The proposed method achieves better system performance than the conventional orthogonal multiple access (OMA)-based multiplexing method thanks to the wider transmission bandwidth per terminal and inter-terminal interference cancellation using a successive interference canceller (SIC). Computer simulation results reveal that the effectiveness of the proposed method is especially significant when the system prioritizes the fairness among terminals (including fairness among services).

This paper proposes a technique that increases the lifetime of large scale integration (LSI) devices. As semiconductor technology improves at miniaturizing transistors, aging effects due to bias temperature instability (BTI) seriously affects their lifetime. BTI increases the threshold voltage of transistors thereby also increasing the delay of an electronics device, resulting in failures due to timing violations. To compensate for aging-induced timing violations, we exploit configurable approximate computing. Assuming that target circuits have exact and approximate modes, they are configured for the approximate mode if an aging sensor predicts violations. Experiments using an example circuit revealed an increase in its lifetime to >10 years.

This paper investigates the performance of interleave division multiple access (IDMA)-based random access with various interference canceller structures in order to support massive machine-type communications (mMTC) in the fifth generation (5G) mobile communication system. To support massive connectivity in the uplink, a grant-free and contention-based multiple access scheme is essential to reduce the control signaling overhead and transmission latency. To suppress the packet loss due to collision and to achieve multi-packet reception, non-orthogonal multiple access (NOMA) with interference cancellation at the base station receiver is essential. We use IDMA and compare various interference canceller structures such as the parallel interference canceller (PIC), successive interference canceller (SIC), and their hybrid from the viewpoints of the error rate and decoding delay time. Based on extensive computer simulations, we show that IDMA-based random access is a promising scheme for supporting mMTC and the PIC-SIC hybrid achieves a good tradeoff between the error rate and decoding delay time.

In this paper, we propose a deep model of visual recognition based on hybrid KPCA Network(H-KPCANet), which is based on the combination of one-stage KPCANet and two-stage KPCANet. The proposed model consists of four types of basic components: the input layer, one-stage KPCANet, two-stage KPCANet and the fusion layer. The role of one-stage KPCANet is to calculate the KPCA filters for convolution layer, and two-stage KPCANet is to learn PCA filters in the first stage and KPCA filters in the second stage. After binary quantization mapping and block-wise histogram, the features from two different types of KPCANets are fused in the fusion layer. The final feature of the input image can be achieved by weighted serial combination of the two types of features. The performance of our proposed algorithm is tested on digit recognition and object classification, and the experimental results on visual recognition benchmarks of MNIST and CIFAR-10 validated the performance of the proposed H-KPCANet.

Broadband amplifiers have been used in modern wireless communication systems. However, the accompanying disadvantage is that there is more nonlinear interference in the available operating frequency band. In addition to the in-band intermodulation distortion which affecting adjacent frequency bands the most important is harmonic distortion. In this letter we present a robust and low complex digital harmonic canceling model called cross-disturbing harmonic (CDH) model for broadband power amplifiers (PAs). The approach introducing cross terms is used to enhance the robustness of the model, thereby significantly increase the stability of the system. The CDH model still has excellent performance when actively reducing the number of coefficients. Comparisons are conducted between the CDH model and the other state-of-the-art model called memory polynomial harmonic (MPM) model. Experimental results show that the CDH model can achieve comparable performance as the MPM model but with much fewer (43%) coefficients.