This manuscript presents a simple scheme to improve the performance of a feedback control system that uses power line channels for its feedback loop. The noise and attenuation of power lines, and thus the signal to noise ratio, are known to be cyclostationary. Such cyclic features in the channel allow us to predict virtually error free transmission instants as well as instants of high probability of errors. This paper introduces and evaluates the effectiveness of a packet transmission scheduling that collaborates with a predictive control scheme adapted to this cyclostationary environment. In other words, we explore the cooperation between the physical and application layers of the system in order to achieve an overall optimization. To rate the control quality of the system we evaluate its stability as well as its ability to follow control commands accurately. We compare a scheme of increased packet rate against our proposed scheme which emulates a high packet rate with the use of predictive control. Through this comparison, we verify the effectiveness of the proposed scheme to improve the control quality of the system, even under low signal to noise ratio conditions in the cyclostationary channel.

A 60-GHz CMOS transmitter with on-chip antenna for high-speed short-range wireless interconnections is presented. The radiation gain of the on-chip antenna is doubled using helium-3 ion irradiation technique. The transmitter core is composed of a resistive-feedback RF amplifier, a double-balanced passive mixer, and an injection-locked oscillator. The wideband and power-saving design of the transmitter core guarantees the low-power and high-data-rate characteristic. The transmitter fabricated in a 65-nm CMOS process achieves 5-Gb/s data rate with an EVM performance of $-$12 dB for BPSK modulation at a distance of 1,mm. The whole transmitter consumes 17,mW from a 1.2-V supply and occupies a core area of 0.64,mm$^{2}$ including the on-chip antenna. The gain-enhanced antenna together with the wideband and power-saving design of the transmitter provides a low-power low-cost full on-chip solution for the short-range high-data-rate wireless communication.

The bag-of-words model (BOW) has been extensively adopted by recent human action recognition methods. The pooling operation, which aggregates local descriptor encodings into a single representation, is a key determiner of the performance of the BOW-based methods. However, the spatio-temporal relationship among interest points has rarely been considered in the pooling step, which results in the imprecise representation of human actions. In this paper, we propose a novel pooling strategy named contextual max pooling (CMP) to overcome this limitation. We add a constraint term into the objective function under the framework of max pooling, which forces the weights of interest points to be consistent with their probabilities. In this way, CMP explicitly considers the spatio-temporal contextual relationships among interest points and inherits the positive properties of max pooling. Our method is verified on three challenging datasets (KTH, UCF Sports and UCF Films datasets), and the results demonstrate that our method achieves better results than the state-of-the-art methods in human action recognition.

We propose a quasi-linear trellis-coded modulation (TCM) using nonbinary convolutional codes for quadrature amplitude modulation (QAM). First, we study a matched mapping which is able to reduce the computational complexity of the Euclidean distances between signal points of MQAM. As an example, we search for rate R=1/2 convolutional codes for coded 64QAM by this method. The symbol error rates of the proposed codes are estimated by the distance properties theoretically and they are verified by simulation. In addition, we compare the minimum free Euclidean distances of these new codes with their upper bounds. Finally, the bit error probabilitiy of the proposed coded modulation is compared with uncoded signal constellations and a conventional TCM code proposed by Ungerboeck. The result shows the proposed scheme outperform them on the AWGN channels.

We found that the work of Kim et al. [1] on trace representation of the Legendre sequence with the periods p ≡ ±3 (mod 8) can be improved by restricting the selection of the periods p while maintaining the form p ≡ ±3 (mod 8) unchanged. Our method relies on forcing the multiplicative group of residue classes modulo p, Zp*, to take 2 as the least primitive root. On the other hand, by relaxing the very strong condition in the theorem of these authors and by using the product among powers of the primitive root and powers of any quadratic residue element to represent an element in Zp*, we could extend Kim's formula so that it becomes a special case of our formula more general.

Android applications that using WebView can load and display web pages. Interaction with web pages allows JavaScript code within the web pages to access resources on the Android device by using the Java object, which is registered into WebView. If this WebView feature were exploited by an attacker, JavaScript code could be used to launch attacks, such as stealing from or tampering personal information in the device. To address these threats, we propose an access control on the security-sensitive APIs at the Java object level. The proposed access control uses static analysis to identify these security-sensitive APIs, detects threats at runtime, and notifies the user if threats are detected, thereby preventing attacks from web pages.

Function speculation design with error recovery mechanisms is quite promising due to its high performance and low area overhead. Previous work has focused on two-stage function speculation and thus lacks a systematic way to address the challenge of the multistage function speculation approach. This paper proposes a multistage function speculation with adaptive predictors and applies it in a novel adder. We deduced the analytical performance and area models for the design and validated them in our experiments. Based on those models, a general methodology is presented to guide design optimization. Both analytical proofs and experimental results on the fabricated chips show that the proposed adder's delay and area have a logarithmic and linear relationship with its bit number, respectively. Compared with the DesignWare IP, the proposed adder provides the same performance with 6-17% area reduction under different bit lengths.

Secure authentication of low cost Radio Frequency Identification (RFID) tag with limited resources is a big challenge, especially when we simultaneously consider anonymity, un-traceability, and forward secrecy. The popularity of Internet of Things (IoT) further amplifies this challenge, as we should authenticate these mobile tags in the partial-distributed-server environments. In this paper, we propose an RFID authentication scheme in the partial-distributed-server environments. The proposed scheme owns excellent performance in terms of computational complexity and scalability as well as security properties.

People expose their personal information on social network services (SNSs). This paper warns of the dangers of this practice by way of an example. We show that the residence registration numbers (RRNs) of many Koreans, which are very important and confidential personal information analogous to social security numbers in the United States, can be estimated solely from the information that they have made open to the public. In our study, we utilized machine learning algorithms to infer information that was then used to extract a part of the RRNs. Consequently, we were able to extract 45.5% of SNS users' RRNs using a machine learning algorithm and brute-force search that did not consume exorbitant amounts of resources.

A closed form frequency estimator is derived for estimating the frequency of a complex exponential signal, embedded in white Gaussian noise. The new estimator consists of the fast Fourier transform (FFT) as the coarse estimation and the phase of autocorrelation lags as the fine-frequency estimator. In the fine-frequency estimation, autocorrelations are calculated from the power-spectral density of the signal, based on the Wiener-Khinchin theorem. For simplicity and suppressing the effect of noise, only the spectrum lines around the actual tone are used. Simulation results show that, the performance of the proposed estimator is approaching the Cramer-Rao Bound (CRB), and has a lower SNR threshold compared with other existing estimators.

Recommender systems, which provide users with recommendations of content suited to their needs, have received great attention in today's online business world. However, most recommendation approaches exploit only a single source of input data and suffer from the data sparsity problem and the cold start problem. To improve recommendation accuracy in this situation, additional sources of information, such as friend relationship and user-generated tags, should be incorporated in recommendation systems. In this paper, we revise the user-based collaborative filtering (CF) technique, and propose two recommendation approaches fusing user-generated tags and social relations in a novel way. In order to evaluate the performance of our approaches, we compare experimental results with two baseline methods: user-based CF and user-based CF with weighted friendship similarity using the real datasets (Last.fm and Movielens). Our experimental results show that our methods get higher accuracy. We also verify our methods in cold-start settings, and our methods achieve more precise recommendations than the compared approaches.

In this paper, an energy harvesting architecture in an Underlay Cooperative Cognitive Network (UCCN) is investigated, in which power constrained Decode-and-Forward relays harvest energy from radio-frequency signals received from a source, and then consume the harvested energy by forwarding the recoded signals to their destination. These recoded signals are launched by a transmitting power which is the harvested energy per a time interval. Based on the energy harvesting architectures that have been studied, two operation protocols are proposed: UCCN with Power Splitting architecture (UCCN-PS), and UCCN with Time Switching architecture (UCCN-TS). The best cooperative relay in both protocols is taken to be the one that satisfies the following conditions: maximum harvested energy, and maximum decoding capacity. As a result of the best relay selection, the signal quality of the selected link from the best relay to the destination is enhanced by the maximum harvested energy. The system performance of the secondary network in the UCCN-PS and UCCN-TS protocols is analyzed and evaluated by the exact closed-form outage probabilities and throughput analyses over Rayleigh fading channels. The Monte Carlo simulation method is performed to verify the theoretical expressions. Evaluations based on outage probability and throughput show that the system performance of the secondary network in the UCCN-PS and UCCN-TS protocols improves when the number of cooperative relays and the interference constraint increase as well as when the primary receiver is farther from the transmitting nodes such as the source and relays of the secondary network. In addition, the throughput performance of the UCCN-PS protocol outperforms that of the UCCN-TS protocol. Finally, the effects of the power splitting ratio, energy harvesting time, energy conversion efficiency, target Signal-to-Noise Ratio (SNR), and location of cooperative relays on the system performance of the secondary network are presented and discussed.

A robust time synchronization algorithm is proposed for orthogonal frequency division multiplexing (OFDM) based aeronautical mobile airport communication systems (AeroMACS). Using a very sharp timing metric obtained from the preamble, the proposed algorithm shows very robust time synchronization performance for various channel models in an airport. Simulation results show that the proposed algorithm achieves an SNR gain of 2 to 3dB at the failure rate of 10-2 to 10-3 compared with previous algorithms.

To improve the outage performance of a wireless body area network (BAN), exploitation of the diversity in the channel obtained by letting different nodes cooperate and relay signals for each other is an attractive solution. We carry out multi-link channel measurements and modeling for all realistic locations of the on-body sensor nodes and for three different motion scenarios in a typical office environment to develop equivalent channel model for simple and practical cooperative transmission schemes. Using the developed model the performance of the transmission schemes are evaluated and compared. Incremental decode and forward relaying is found to be consistently better than the other schemes with gains of up to 16dB at 10% outage probability, and an average gain of more than 5.9dB for any location of the coordinator node. The best location of the coordinator node based on the performance is also determined. Such insights will be very useful in designing BANs.

This paper proposed patient friendly capsule endoscopy (CE) for not only screening but also treatment. Two different types of CEs with an Internet utility were investigated. The first type used magnetic navigation in the stomach and colon for screening. Magnetic navigation enabled the capsule to explore the whole of the gastrointestinal tract with less risk of missing lesions and complete the screening within the battery life. The system's design was patiently friendly as it allowed the subjects to leave the hospital after the capsule had been navigated in the stomach. The second investigated two different therapeutic robotic endoscopes. Both prototypes were driven by DC motors and controlled remotely via the internet. In addition, they were equipped with therapeutic tools and each prototype's ability with the tools was assessed. The investigation showed it was possible to remotely control both prototypes and operate therapeutic tools via the Internet. The investigation identified areas for improvement, such as size, connection speed, security of data, and the holding the capsule's position during treatment, In conclusion, both methods have the potential to make capsule endoscopy a very patient friendly procedure that can be carried out anywhere.

Recommendation systems have been widely used in E-commerce sites, social media and etc. An important recommendation task is to predict items that a user will perform actions on with users' historical data, which is called top-K recommendation. Recently, there is huge amount of emerging items which are divided into a variety of categories and researchers have argued or suggested that top-K recommendation of item category could be very beneficial for users to make better and faster decisions. However, the traditional methods encounter some common but crucial problems in this scenario because additional information, such as time, is ignored. The ranking algorithm on graphs and the increasingly growing amount of online user behaviors shed some light on these problems. We propose a construction method of time-aware graphs to use ranking algorithm for personalized recommendation of item category. Experimental results on real-world datasets demonstrate the advantages of our proposed method over competitive baseline algorithms.

Square-root Nyquist transmit filtering is typically used in single-carrier (SC) transmission. By changing the filter roll-off factor, the bit-error rate (BER), peak-to-average power ratio (PAPR), and spectrum efficiency (SE) changes, resulting in a tradeoff among these performance indicators. In this paper, assuming SC with frequency-domain equalization (SC-FDE), we design a new transmit filtering based on the minimum variance of instantaneous transmit power (VIP) criterion in order to reduce the PAPR of the transmit signal of SC-FDE. Performance evaluation of SC-FDE using the proposed transmit filtering is done by computer simulation, and shows that the proposed transmit filtering contributes lower transmit PAPR, while there exists only a small degradation in BER performance compared to SC-FDE using square-root Nyquist filtering.

In this letter, we propose an energy-efficient in-network processing method for continuous grouped aggregation queries in wireless sensor networks. As in previous work, in our method sensor nodes partially compute aggregates as data flow through them to reduce data transferred. Different from other methods, our method considers group information of partial aggregates when sensor nodes forward them to next-hop nodes in order to maximize data reduction by same-group partial aggregation. Through experimental evaluation, we show that our method outperforms the existing methods in terms of energy efficiency.

In this paper, we propose an analog cancellation scheme for multipath self-interference channels in full-duplex wireless orthogonal frequency-division multiplexing (OFDM) systems. The conventional approaches emulate the radio-frequency (RF) self-interference signals by passing the RF transmit signals through delay lines and programmable attenuators. By contrast, our proposed scheme computes the phase-rotated and weighted versions of the baseband transmit signals in the baseband domain, which are simply upconverted to obtain the emulated RF self-interference signals. Numerical results are presented to verify the suppression performance of the proposed scheme.

This paper discusses the perspectives of using a wake-up receiver (WUR) in wireless body area network (WBAN) applications with event-driven data transfers. First we compare energy efficiency between the WUR-based and the duty-cycled medium access control protocol -based IEEE 802.15.6 compliant WBAN. Then, we review the architectures of state-of-the-art WURs and discuss their suitability for WBANs. The presented results clearly show that the radio frequency envelope detection based architecture features the lowest power consumption at a cost of sensitivity. The other architectures are capable of providing better sensitivity, but consume more power. Finally, we propose the design modification that enables using a WUR to receive the control commands beside the wake-up signals. The presented results reveal that use of this feature does not require complex modifications of the current architectures, but enables to improve energy efficiency and latency for small data blocks transfers.