Showing papers in "Etri Journal in 2014"
TL;DR: This work proposes a new approach that can terminate the quadtree‐based structure early, based on the RD costs of the parent and current levels, and shows that this algorithm provides a significant time reduction for encoding, with only a small loss in video quality.
Abstract: A new-generation video coding standard, named High Efficiency Video Coding (HEVC), has recently been developed by JCT-VC. This new standard provides a significant improvement in picture quality, especially for high-resolution videos. However, one the most important challenges in HEVC is time complexity. A quadtree-based structure is created for the encoding and decoding processes and the rate-distortion (RD) cost is calculated for all possible dimensions of coding units in the quadtree. This provides a high encoding quality, but also causes computational complexity. We focus on a reduction scheme of the computational complexity and propose a new approach that can terminate the quadtree-based structure early, based on the RD costs of the parent and current levels. Our proposed algorithm is compared with HEVC Test Model version 10.0 software and a previously proposed algorithm. Experimental results show that our algorithm provides a significant time reduction for encoding, with only a small loss in video quality.
48 citations
TL;DR: In this article, a micro-encapsulated catalyst was adopted to control the chemical reaction at room and processing temperatures for fine-pitch flip-chip bonding with semiconductor packaging.
Abstract: For the fine-pitch application of flip-chip bonding with semiconductor packaging, fluxing and hybrid underfills were developed. A micro-encapsulated catalyst was adopted to control the chemical reaction at room and processing temperatures. From the experiments with a differential scanning calorimetry and viscometer, the chemical reaction and viscosity changes were quantitatively characterized, and the optimum type and amount of micro-encapsulated catalyst were determined to obtain the best pot life from a commercial viewpoint. It is expected that fluxing and hybrid underfills will be applied to fine-pitch flip-chip bonding processes and be highly reliable.
34 citations
TL;DR: The proposed scheme efficiently supports variable bit rate traffic during the reservation period, reducing resource waste and outperform other schemes on a range of measures, showing the effect of using a directional antenna.
Abstract: In this paper, we consider a resource allocation scheme for millimeter-wave-based wireless personal area networks (WPANs) using directional antennas. This scheme involves scheduling the reservation period of medium access control (MAC) for IEEE 802.15.3c, one of the standards for millimeter-wave-based WPANs adopting directional antennas. Objective functions are considered to minimize the average delay and maximize throughput, and two scheduling algorithms, namely, MInMax concurrent transmission and MAxMin concurrent transmission, are proposed to provide a suboptimal solution to each objective function. These are based on an exclusive region and two decision rules that determine the length of reservation times and transmission order of groups. Each group consists of flows that are concurrently transmittable via spatial reuse. The algorithms appropriately apply two decision rules according to their objectives. A real video trace is used for the numerical results, which show that the proposed algorithms satisfy their objectives. They outperform other schemes on a range of measures, showing the effect of using a directional antenna. The proposed scheme efficiently supports variable bit rate traffic during the reservation period, reducing resource waste.
32 citations
TL;DR: A modified version of Zhang's reversible data hiding method in encrypted images is proposed in this letter, and the former idea of block division is thoroughly abandoned, whereas the random diffusion strategy is used.
Abstract: A modified version of Zhang's reversible data hiding method in encrypted images is proposed in this letter. To make full use of spatial correlation in natural images, the former idea of block division is thoroughly abandoned, whereas the random diffusion strategy is used. Additionally, the fluctuation measurement of pixels containing embedded data is improved by accurate prediction. The experiment results reveal that our proposed method is superior to both Zhang's method and the later improved version proposed by Hong and others.
30 citations
TL;DR: A holographic display system with a 22-inch LCD panel is developed to provide a wide viewing angle and large holographic 3D image by steering a narrow viewing window resulting from a very large pixel pitch compared to the wave length of the laser light.
Abstract: A holographic display system with a 22-inch LCD panel is developed to provide a wide viewing angle and large holographic 3D image. It is realized by steering a narrow viewing window resulting from a very large pixel pitch compared to the wave length of the laser light. Point light sources and a lens array make it possible to arbitrarily control the position of the viewing window for a moving observer. The holographic display provides both eyes of the observer with a holographic 3D image using two vertically placed LCD panels and a beam splitter to support the holographic stereogram.
30 citations
TL;DR: In this article, the authors presented a new locomotion mode recognition method based on a transformed correlation feature analysis using an electromyography (EMG) pattern, where each movement is recognized using six weighted sub-correlation filters, which are applied to the correlation feature analyses through the use of six time-domain features.
Abstract: This paper presents a new locomotion mode recognition method based on a transformed correlation feature analysis using an electromyography (EMG) pattern. Each movement is recognized using six weighted subcorrelation filters, which are applied to the correlation feature analysis through the use of six time-domain features. The proposed method has a high recognition rate because it reflects the importance of the different features according to the movements and thereby enables one to recognize real-time EMG patterns, owing to the rapid execution of the correlation feature analysis. The experiment results show that the discriminating power of the proposed method is 85.89% () when walking on a level surface, 96.47% () when going up stairs, and 96.37% () when going down stairs for given normal movement data. This makes its accuracy and stability better than that found for the principal component analysis and linear discriminant analysis methods.
27 citations
TL;DR: In this paper, a simple capacitive tilt sensor with a metallic ball is proposed, which assists in managing the inherent contact problem in measuring tilt angles, and the experimental results demonstrate the relationship between the tilt angles and measured capacitances compared with the analytical study.
Abstract: In this paper, a new, simple capacitive tilt sensor with a metallic ball is proposed. The proposed tilt sensor has only two electrodes and a metallic ball, and this design assists in managing the inherent contact problem in measuring tilt angles. Capacitive sensing, compared with other types of tilt sensor, has many advantages such as simplicity, noncontact measurement, long-throw linear displacement, and sub-micron plate spacing. Its design and fabrication process are significantly simpler than previous types of tilt sensors. The dimensions of the prototype tilt sensor are , and the diameter of the polystyrene tube is 5 mm with a tube thickness of 0.15 mm. An analytical study of the prototype capacitive tilt sensor was undertaken, and the experimental results demonstrate the relationship between the tilt angles and measured capacitances compared with the analytical study.
25 citations
TL;DR: This paper provides the system architecture and relevant operations for the virtual CDNs and evaluates the performance based on a simulation, which enables the capabilities of VMs to be scaled to encompass the dynamically changing resource demand of the aggregated virtual CDN services.
Abstract: This paper proposes a novel framework for virtual content delivery networks (CDNs) based on cloud computing. The proposed framework aims to provide multimedia content delivery services customized for content providers by sharing virtual machines (VMs) in the Infrastructure-as-a-Service cloud, while fulfilling the service level agreement. Furthermore, it supports elastic virtual CDN services, which enables the capabilities of VMs to be scaled to encompass the dynamically changing resource demand of the aggregated virtual CDN services. For this, we provide the system architecture and relevant operations for the virtual CDNs and evaluate the performance based on a simulation.
23 citations
TL;DR: In this paper, the authors presented low-temperature grown GaAs (LTG-GaAs)-based photoconductive antennas for the generation and detection of terahertz (THz) waves.
Abstract: In this letter, we present low-temperature grown GaAs (LTG-GaAs)-based photoconductive antennas for the generation and detection of terahertz (THz) waves. The growth of LTG-GaAs and the annealing temperatures are systematically discussed based on the material characteristics and the properties of THz emission and detection. The optimum annealing temperature depends on the growth temperature, which turns out to be to for the initial excess arsenic density of to .
23 citations
TL;DR: An unsupervised framework for speech noise reduction based on the recent development of low‐rank and sparse matrix decomposition is proposed, which directly separates the speech signal from noisy speech by decomposing the noisy speech spectrogram into three submatrices: the noise structure Matrix, the clean speech structure matrix, and the residual noise matrix.
Abstract: In this letter, we propose an unsupervised framework for speech noise reduction based on the recent development of low-rank and sparse matrix decomposition. The proposed framework directly separates the speech signal from noisy speech by decomposing the noisy speech spectrogram into three submatrices: the noise structure matrix, the clean speech structure matrix, and the residual noise matrix. Evaluations on the Noisex-92 dataset show that the proposed method achieves a signal-to-distortion ratio approximately 2.48 dB and 3.23 dB higher than that of the robust principal component analysis method and the non-negative matrix factorization method, respectively, when the input SNR is -5 dB.
22 citations
TL;DR: This paper proposes a novel method for predicting the lifespan and retweet times of tweets, the latter being a proxy for measuring the popularity of a tweet, and compares it with conventional models.
Abstract: In social network services, such as Facebook, Google+, Twitter, and certain postings attract more people than others. In this paper, we propose a novel method for predicting the lifespan and retweet times of tweets, the latter being a proxy for measuring the popularity of a tweet. We extract information from retweet graphs, such as posting times; and social, local, and content features, so as to construct prediction knowledge bases. Tweets with a similar topic, retweet pattern, and properties are sequentially extracted from the knowledge base and then used to make a prediction. To evaluate the performance of our model, we collected tweets on Twitter from June 2012 to October 2012. We compared our model with conventional models according to the prediction goal. For the lifespan prediction of a tweet, our model can reduce the time tolerance of a tweet lifespan by about four hours, compared with conventional models. In terms of prediction of the retweet times, our model achieved a significantly outstanding precision of about 50%, which is much higher than two of the conventional models showing a precision of around 30% and 20%, respectively.
TL;DR: The proposed EIPM method computes the priority of all inter prediction modes and performs ME only on a selected inter prediction mode, which reduces computational complexity arising from ME by up to 51.76% and achieves near similar coding performance compared to HEVC test model version 10.1.
Abstract: High Efficiency Video Coding (HEVC) is the most recent video coding standard to achieve a higher coding performance than the previous H.264/AVC. In order to accomplish this improved coding performance, HEVC adopted several advanced coding tools; however, these cause heavy computational complexity. Similar to previous video coding standards, motion estimation (ME) of HEVC requires the most computational complexity; this is because ME is conducted for three inter prediction modes - namely, uniprediction in list 0, uniprediction in list 1, and biprediction. In this paper, we propose an efficient inter prediction mode (EIPM) decision method to reduce the complexity of ME. The proposed EIPM method computes the priority of all inter prediction modes and performs ME only on a selected inter prediction mode. Experimental results show that the proposed method reduces computational complexity arising from ME by up to 51.76% and achieves near similar coding performance compared to HEVC test model version 10.1.
TL;DR: In this paper, an implantable rectangular spiral antenna for medical biotelemetry in the Medical Implant Communications Service band (402 MHz to 405 MHz) has been designed, and the antenna impedance is easily adjusted by controlling the shape and length of the U-shaped loop.
Abstract: For this study, we designed an implantable rectangular spiral antenna for medical biotelemetry in the Medical Implant Communications Service band (402 MHz to 405 MHz). The designed antenna has a U-shaped loop for impedance matching. The antenna impedance is easily adjusted by controlling the shape and length of the U-shaped loop. Significant design parameters were studied to understand their effects on the antenna performance. To verify the potential of the antenna for the desired applications, we fabricated a prototype and measured its performance in terms of the resonant characteristics and gain radiation patterns of the antenna. In the testing phase, the prototype antenna was embedded in human skin tissue-emulating gel, which was developed to simulate a real operation environment. The measured resonant characteristics show good agreement with the simulations, and the -10 dB frequency band is within the range of 398 MHz to 420 MHz. The antenna exhibits a maximum gain of -22.26 dBi and an antenna efficiency of 0.215%.
TL;DR: In this paper, the authors investigated the impact of tweets on box office revenue and found that the disconfirmation that occurs in relation to the total number of pre-consumption tweets for a movie has a negative impact on box-office revenue.
Abstract: This study investigates the impact of tweets on box office revenue. Specifically, the study focuses on the times when tweets were written by examining the impact of pre- and post-consumption tweets on box office revenue; an examination that is based on Expectation Confirmation Theory. The study also investigates the impact of intention tweets versus subjective tweets and the impact of negative tweets on box office revenue. Targeting 120 movies released in the US between February and August 2012, this study collected tweet information on a daily basis from two weeks before the opening until the closing and box office revenue information. The results indicate that the disconfirmation that occurs in relation to the total number of pre-consumption tweets for a movie has a negative impact on box office revenue. This premise suggests that the formation of higher expectations of a movie does not always result in positive results in situations where tweets on perceived movie quality after watching spread rapidly. This study also reveals that intention tweets have stronger effects on box office revenue than subjective tweets.
TL;DR: In this paper, a planarization of the embossed nano-structure on a glass substrate was presented, showing a very smooth surface for organic light-emitting diode (OLED) light extraction.
Abstract: We developed a highly refractive index planarization layer showing a very smooth surface for organic light-emitting diode (OLED) light extraction, and we successfully prepared a highly efficient white OLED device with an embossed nano-structure and highly refractive index planarization layers. White OLEDs act as an internal out-coupling layer. We used a spin-coating method and two types of TiO2 solutions for a planarization of the embossed nano-structure on a glass substrate. The first TiO2 solution was TiO2 sol, which consists of TiO2 colloidal particles in an acidic aqueous solution and several organic additives. The second solution was an organic and inorganic hybrid solution of TiO2. The surface roughness (Ra) and refractive index of the TiO2 planarization films on a flat glass were 0.4 nm and 2.0 at 550 nm, respectively. The J–V characteristics of the OLED including the embossed nano-structure and the TiO2 planarization film were almost the same as those of an OLED with a flat glass, and the luminous efficacy of the aforementioned OLED was enhanced by 34% compared to that of an OLED with a flat glass.
TL;DR: In this article, an effective vision-based localization technology is proposed to apply to autonomous vehicles, which makes use of numerical maps that are widely used in the field of geographic information systems and that have already been built in advance.
Abstract: Autonomous vehicle technology based on information technology and software will lead the automotive industry in the near future. Vehicle localization technology is a core expertise geared toward developing autonomous vehicles and will provide location information for control and decision. This paper proposes an effective vision-based localization technology to be applied to autonomous vehicles. In particular, the proposed technology makes use of numerical maps that are widely used in the field of geographic information systems and that have already been built in advance. Optimum vehicle ego-motion estimation and road marking feature extraction techniques are adopted and then combined by an extended Kalman filter and particle filter to make up the localization technology. The implementation results of this paper show remarkable results; namely, an 18 ms mean processing time and 10 cm location error. In addition, autonomous driving and parking are successfully completed with an unmanned vehicle within a 300 m × 500 m space.
TL;DR: The results show that the introduction of such a handover mechanism into the simulation environment positively influences the system performance, because terminals spend more time in the cell; hence, a better reception is offered.
Abstract: Long-Term Evolution employs a hard handover procedure. To reduce the interruption of data flow, downlink data is forwarded from the serving eNodeB (eNB) to the target eNB during handover. In cellular networks, unbalanced loads may lead to congestion in both the radio network and the backhaul network, resulting in bad end-to-end performance as well as causing unfairness among the users sharing the bottleneck link. This work focuses on congestion in the transport network. Handovers toward less loaded cells can help redistribute the load of the bottleneck link; such a mechanism is known as load balancing. The results show that the introduction of such a handover mechanism into the simulation environment positively influences the system performance. This is because terminals spend more time in the cell; hence, a better reception is offered. The utilization of load balancing can be used to further improve the performance of cellular systems that are experiencing congestion on a bottleneck link due to an uneven load.
TL;DR: The simulation results in this paper illustrate that the proposed scheme affords a more energy-efficient system to be implemented, compared to a conventional power management scheme, by allocating the bandwidth uniformly regardless of the amount of interference or traffic demand.
Abstract: An integrated multi-beam satellite and multi-cell terrestrial system is an attractive means for highly efficient communication due to the fact that the two components (satellite and terrestrial) make the most of each other's resources In this paper, a terrestrial component reuses a satellite's resources under the control of the satellite's network management system This allows the resource allocation for the satellite and terrestrial components to be coordinated to optimize spectral efficiency and increase overall system capacity In such a system, the satellite resources reused in the terrestrial component may bring about severe interference, which is one of the main factors affecting system capacity Under this consideration, the objective of this paper is to achieve an optimized resource allocation in both components in such a way as to minimize any resulting inter-component interference The objective of the proposed scheme is to mitigate this inter-component interference by optimizing the total transmission power - the result of which can lead to an increase in capacity The simulation results in this paper illustrate that the proposed scheme affords a more energy-efficient system to be implemented, compared to a conventional power management scheme, by allocating the bandwidth uniformly regardless of the amount of interference or traffic demand
TL;DR: In this article, a C-band 50 W high-power microwave monolithic integrated circuit amplifier for use in a phased-array radar system was designed and fabricated using commercial AlGaN/GaN technology.
Abstract: A C-band 50 W high-power microwave monolithic integrated circuit amplifier for use in a phased-array radar system was designed and fabricated using commercial AlGaN/GaN technology. This two-stage amplifier can achieve a saturated output power of 50 W with higher than 35% power-added efficiency and 22 dB small-signal gain over a frequency range of 5.5 GHz to 6.2 GHz. With a compact chip area, an output power density of is demonstrated.
TL;DR: In this article, the authors proposed an energy efficient transmission power control scheme for IEEE 802.15.6 body area networks (BANs) which can improve energy efficiency by adaptively adjusting the transmit power in an on-demand way to adapt to varying channel environments.
Abstract: Energy consumption is an important issue in body area networks (BANs). In this letter, we propose an energy efficient transmission power control scheme for IEEE 802.15.6 BANs, which can improve energy efficiency by adaptively adjusting the transmit power in an on-demand way to adapt to varying channel environments. Simulations are performed to evaluate the performance, and it is shown that the proposed power control scheme outperforms traditional ones in terms of energy efficiency without significant reliability degradation.
TL;DR: The experimental results show that the feature streams simply combined with the proposed features are effective for an improvement in the recognition accuracy of a hidden Markov model–based speech recognizer.
Abstract: In this paper, alternative dynamic features for speech recognition are proposed. The goal of this work is to improve speech recognition accuracy by deriving the representation of distinctive dynamic characteristics from a speech spectrum. This work was inspired by two temporal dynamics of a speech signal. One is the highly non-stationary nature of speech, and the other is the inter-frame change of a speech spectrum. We adopt the use of a sub-frame spectrum analyzer to capture very rapid spectral changes within a speech analysis frame. In addition, we attempt to measure spectral fluctuations of a more complex manner as opposed to traditional dynamic features such as delta or double-delta. To evaluate the proposed features, speech recognition tests over smartphone environments were conducted. The experimental results show that the feature streams simply combined with the proposed features are effective for an improvement in the recognition accuracy of a hidden Markov model-based speech recognizer.
TL;DR: This paper proposes a global mapping algorithm for multiple robots from an omnidirectional‐vision simultaneous localization and mapping (SLAM) approach based on an object extraction method using Lucas–Kanade optical flow motion detection and images obtained through fisheye lenses mounted on robots.
Abstract: This paper proposes a global mapping algorithm for multiple robots from an omnidirectional-vision simultaneous localization and mapping (SLAM) approach based on an object extraction method using Lucas– Kanade optical flow motion detection and images obtained through fisheye lenses mounted on robots. The multi-robot mapping algorithm draws a global map by using map data obtained from all of the individual robots. Global mapping takes a long time to process because it exchanges map data from individual robots while searching all areas. An omnidirectional image sensor has many advantages for object detection and mapping because it can measure all information around a robot simultaneously. The process calculations of the correction algorithm are improved over existing methods by correcting only the object’s feature points. The proposed algorithm has two steps: first, a local map is created based on an omnidirectional-vision SLAM approach for individual robots. Second, a global map is generated by merging individual maps from multiple robots. The reliability of the proposed mapping algorithm is verified through a comparison of maps based on the proposed algorithm and real maps.
TL;DR: A system to recognize both single and continuous human actions from monocular video sequences, based on 3D human modeling and cyclic hidden Markov models (CHMMs) is proposed.
Abstract: Human action recognition is used in areas such as surveillance, entertainment, and healthcare. This paper proposes a system to recognize both single and continuous human actions from monocular video sequences, based on 3D human modeling and cyclic hidden Markov models (CHMMs). First, for each frame in a monocular video sequence, the 3D coordinates of joints belonging to a human object, through actions of multiple cycles, are extracted using 3D human modeling techniques. The 3D coordinates are then converted into a set of geometrical relational features (GRFs) for dimensionality reduction and discrimination increase. For further dimensionality reduction, k-means clustering is applied to the GRFs to generate clustered feature vectors. These vectors are used to train CHMMs separately for different types of actions, based on the Baum-Welch re-estimation algorithm. For recognition of continuous actions that are concatenated from several distinct types of actions, a designed graphical model is used to systematically concatenate different separately trained CHMMs. The experimental results show the effective performance of our proposed system in both single and continuous action recognition problems.
TL;DR: This work proposes a system named iVisher for detecting a concealed incoming number (that is, caller ID) in Session Initiation Protocol–based Voice‐over‐Internet Protocol initiated phone calls and demonstrates that the system is capable of detecting a hidden caller ID.
Abstract: Voice phishing (vishing) uses social engineering, based on people's trust in telephone services, to trick people into divulging financial data or transferring money to a scammer. In a vishing attack, a scammer often modifies the telephone number that appears on the victim's phone to mislead the victim into believing that the phone call is coming from a trusted source, since people typically judge a caller's legitimacy by the displayed phone number. We propose a system named iVisher for detecting a concealed incoming number (that is, caller ID) in Session Initiation Protocol-based Voice-over-Internet Protocol initiated phone calls. Our results demonstrate that iVisher is capable of detecting a concealed caller ID without significantly impacting upon the overall call setup time.
TL;DR: A power allocation strategy for an orthogonal frequency‐division multiplexing system to maximize the transferred power under the required information capacity and total available power constraints and proposes a low‐complexity power reallocation algorithm.
Abstract: To deal with the major challenges of embedded sensor networks, we consider the use of magnetic fields as a means of reliably transferring both information and power to embedded sensors. We focus on a power allocation strategy for an orthogonal frequency-division multiplexing system to maximize the transferred power under the required information capacity and total available power constraints. First, we consider the case of a co-receiver, where information and power can be extracted from the same signal. In this case, we find an optimal power allocation (OPA) and provide the upper bound of achievable transferred power and capacity pairs. However, the exact calculation of the OPA is computationally complex. Thus, we propose a lowcomplexity power reallocation algorithm. For practical consideration, we consider the case of a separated receiver (where information and power are transferred separately through different resources) and propose two heuristic power allocation algorithms. Through simulations using the Agilent Advanced Design System and Ansoft High Frequency Structure Simulator, we validate the magneticinductive channel characteristic. In addition, we show the performances of the proposed algorithms by providing achievable η-C regions.
TL;DR: In this paper, a cooperative game-theoretic smart grid management scheme is proposed to maximize the overall system performance while satisfying the requirements of individual appliances by exploiting multi-appliance diversity, appliances in each group are dynamically scheduled in a cooperative manner.
Abstract: Recently, the idea of the smart grid has been gaining significant attention and has become a hot research topic. The purpose of this paper is to present a novel smart grid management scheme that uses game theory principles. In our proposed scheme, power appliances in the smart grid adaptively form groups according to the non-cooperative hedonic game model. By exploiting multi-appliance diversity, appliances in each group are dynamically scheduled in a cooperative manner. For efficient smart grid management, the proposed coopetition game approach is dynamic and flexible to adaptively respond to current system conditions. The main feature is to maximize the overall system performance while satisfying the requirements of individual appliances. Simulation results indicate that our proposed scheme achieves higher energy efficiency and better system performance than other existing schemes.
TL;DR: The proposed personalized healthcare system can support cost‐effective disease care in an at‐hospital environment and personalized self‐management of chronic disease in anat‐home environment and a predicted cost model are provided to show the effectiveness of the system.
Abstract: The rapid increase in the number of patients with chronic diseases is an important public healthcare issue in many countries, which accelerates many studies on a healthcare system that can, whenever and wherever, extract and process patient data. A patient with a chronic disease conducts self-management in an out-of-hospital environment, particularly in an at-home environment, so it is important to provide integrated and personalized healthcare services for effective care. To help provide effective care for chronic disease patients, we propose a service flow and a new cloud-based personalized healthcare system architecture supporting both at-home and at-hospital environments. The system considers the different characteristics of at-hospital and at-home environments, and it provides various chronic disease care services. A prototype implementation and a predicted cost model are provided to show the effectiveness of the system. The proposed personalized healthcare system can support cost-effective disease care in an at-hospital environment and personalized self-management of chronic disease in an at-home environment.
TL;DR: This paper proposes a new data migration method that can dynamically move data pages into the most appropriate memories to exploit their strengths and alleviate their weaknesses, and improves over the existing ones the access response time.
Abstract: For memory-based big data storage, using hybrid memories consisting of both dynamic random-access memory (DRAM) and non-volatile random-access memories (NVRAMs) is a promising approach. DRAM supports low access time but consumes much energy, whereas NVRAMs have high access time but do not need energy to retain data. In this paper, we propose a new data migration method that can dynamically move data pages into the most appropriate memories to exploit their strengths and alleviate their weaknesses. We predict the access frequency values of the data pages and then measure comprehensively the gains and costs of each placement choice based on these predicted values. Next, we compute the potential benefits of all choices for each candidate page to make page migration decisions. Extensive experiments show that our method improves over the existing ones the access response time by as much as a factor of four, with similar rates of energy consumption.
TL;DR: The proposed algorithm links the joint estimation of TOA and DOA to the sparse representation framework and has better parameter‐estimation performance than traditional propagator methods, such as, estimation of signal parameters via rotational invariance techniques algorithms matrix pencil algorithms, and other new joint-estimation schemes.
Abstract: This paper addresses the problem of joint time of arrival (TOA) and direction of arrival (DOA) estimation in impulse radio ultra-wideband systems with a two-antenna receiver and links the joint estimation of TOA and DOA to the sparse representation framework. Exploiting this link, an orthogonal matching pursuit algorithm is used for TOA estimation in the two antennas, and then the DOA parameters are estimated via the difference in the TOAs between the two antennas. The proposed algorithm can work well with a single measurement vector and can pair TOA and DOA parameters. Furthermore, it has better parameter-estimation performance than traditional propagator methods, such as, estimation of signal parameters via rotational invariance techniques algorithms matrix pencil algorithms, and other new joint-estimation schemes, with one single snapshot. The simulation results verify the usefulness of the proposed algorithm.
TL;DR: In this paper, a low-noise amplifier and an RF up/down conversion fourth-harmonically pumped mixer are implemented using a gallium arsenide pseudomorphic high-electron-mobility transistor process.
Abstract: This paper presents a novel 90 GHz band 16-quadrature amplitude modulation (16-QAM) orthogonal frequency-division multiplexing (OFDM) communication system. The system can deliver 6 Gbps through six channels with a bandwidth of 3 GHz. Each channel occupies 500 MHz and delivers 1 Gbps using 16-QAM OFDM. To implement the system, a low-noise amplifier and an RF up/down conversion fourth-harmonically pumped mixer are implemented using a gallium arsenide pseudomorphic high-electron-mobility transistor process. A polarization-division duplex architecture is used for full-duplex communication. In a digital modem, OFDM with 256-point fast Fourier transform and (255, 239) Reed-Solomon forward error correction codecs are used. The modem can compensate for a carrier-frequency offset of up to 50 ppm and a symbol rate offset of up to 1 ppm. Experiment results show that the system can achieve a bit error rate of at a signal-to-noise ratio of about 19.8 dB.