To reduce perforamnce degradations of LR-WPANs due to interference from WLANs, this letter proposes a protocol to allow a piconet to switch an operating channel to an interference-free channel only for transmitting beacon frames. The proposed method does not only increase network performances because of hgh reliability of the beacon frames, but also increase overerall channel utilizations because of using even interfered-channels.

This paper proposes an efficient adaptive depth-map coding scheme for generating virtual-view images in 3D-video. Virtual-view images can be generated by view-interpolation based on the decoded depth-map of the image. The proposed depth-map coding scheme is designed to have a new gray-coding-based bit-plane coding method for efficiently coding the depth-map images on the object-boundary areas, as well as the conventional DCT-based coding scheme (H.264/AVC) for efficiently coding the inside area images of the objects or the background depth-map images. Simulation results show that the proposed coding scheme, in comparison with the H.264/AVC coding scheme, improves the BD-rate savings 6.77%-10.28% and the BD-PSNR gains 0.42 dB-0.68 dB. It also improves the subjective picture quality of synthesized virtual-view images using decoded depth-maps.

Since femtocells are deployed in a two tier cellular network, along with macrocells operating on the same channel, interference between them limits the overall performance of the network. Without any control of the femtocell operation, pre-deployed macrocells will experience severe interference, which is not consistent with the current femtocell deployment principle. In this paper, to resolve this problem, a mathematical framework that optimizes the downlink transmission power of femtocells is formulated. Based on the formulated framework, we derive the optimal value of the transmission power so that the transmission affects the pre-deployed macrocell's downlink performance at a minimum scale, while providing sufficient Quality of Service (QoS) to its served users. Furthermore, to reduce the complexity of the power control process, we propose an Interference Estimation scheme which approximates the interference levels between different pairs of macrocell and femtocell base stations. The feasibility of this estimation process is shown by deriving the lower and upper bound of the estimation error. Through simulations, compared to no power control, we show that our proposed method provides a 17.64% reduction in macro user's outage probability, 5.9 dB decrease of interference on cell-edge macrocell users, and a 1.41 times increase in average user throughput.

This letter presents a novel edge-based blur metric that averages the ratios between the slopes and heights of edges. The metric computes the edge slopes more carefully, i.e., by averaging the edge gradients. The effectiveness of the proposed metric is confirmed by experiments with motion or Gaussian blurred real images and comparison with existing edge-based blur metrics.

In nearest neighbor distance ratio (NNDR) matching the fixed distance ratio threshold sometimes results in an insufficient number of inliers or a huge number of outliers, which is not good for robust tracking. In this letter, we propose adjusting the distance ratio threshold based on maximizing the number of inliers while maintaining the ratio of the number of outliers to that of inliers. By applying the proposed method to a model-based camera tracking system, its effectiveness is verified.

This paper defines a Quality of Experience (QoE) parameter for multi-view video streaming service over Wireless Broadband Internet, and proposes cross-layer optimization (CLO) algorithm to maximize the QoE. The proposed CLO algorithm interacts with all layers from PHY layer to video layer. Under the time-varying wireless channel condition, it guarantees service continuity to the user by selecting frames to be transmitted. The CLO technique takes inter-view and the temporal significance of the multi-view video frames into consideration when deciding the Transmission Frame Set (TFS) and its Levels of FEC (LOF). Through simulation of the proposed technique, it is shown that the optimal quality of the multi-view video can be achieved even during hand-over, using the minimum amount of resources. Visual quality of multi-view video streams is improved by about 15.330.2%, especially up to 39.165% during the hand-over. Moreover, continuity of the most important view has been increased by 20.139.1% in comparison with conventional method.

In this paper, we have shown a major element occupying the large portion of software communications architecture (SCA)-based software defined radio (SDR) handheld embedded system and an important feature for implementing a high speed broadband radio to an SCA waveform through a couple of experiments. First, this paper identifies the main items possessing the large portion of SCA-based SDR handheld embedded system by the experiment on the target platform which is similar to a commercial mobile handheld system. Both the world interoperabillity for microwave access (WiMAX) and high speed downlink packet access (HSDPA) waveform software packages are used as an SCA waveform application. This paper also presents the results of the relative binary size distribution of SCA software resources for looking for the major elements making an SCA-based SDR handheld embedded system heavier. As a result, when focusing on the relative weight portion of SCA core framework (CF), the SCA CF takes 16% up and others have 84% out of the whole binary size distribution of SCA software resources. The results of the experiment give us notice that the weight portion of SCA CF is minor and compatible with the overall software binary size needs of an SCA-based SDR handheld embedded system, on the other hand, the practical problem on the lightweight is in a common object request broker architecture (CORBA) and extensible markup language (XML) parser resources. Second, this paper describes an important feature for implementing a high speed broadband radio to an SCA waveform and presents the performance evaluation results of the SCA port communication on both power PC (PPC) 405 and x86 processor platforms. The PPC 405 platform, which is similar to a commercial mobile handset, takes the value of average round trip time (RTT) with a maximum of thirty six millisecond. The x86 platform, however, which is analogous to a server platform, maintains stable micro-second resolution. From our experiments, we observe that rapid SCA port communication, sufficiently less than the frame length of high-speed broadband radios, should be provided for serving those radio services in a commercial handheld system based on the SCA.

This paper introduces the water ring scan method especially designed for the scalable video coding schemes such as fine granularity scalabilities (FGS) on the basis of MPEG-4 part-2 and the H.264. The proposed scanning method can improve the subjective quality of the decoded video by most-preferentially encoding, transmitting and decoding the image information of the region of interest. From the various simulation results of FGS coding schemes with MPEG-4 part 2 and H.264, the proposed scanning method can improve the subjective picture quality about 0.5 dB 3.5 dB better than the widely used raster scan order, especially on the region of interest, without significant loss of the quality in the left-over region.

Solid-state disks (SSDs) have received much attention as replacements for hard disk drives (HDDs). One of their noticeable advantages is their high-speed read/write operation. To achieve good performance, SSDs have an internal memory hierarchy which includes several volatile memories, such as DRAMs and SRAMs. Furthermore, many SSDs adopt aggressive memory management schemes under the assumption of stable power supply. Unfortunately, the data stored in the volatile memories are lost when the power supplied to SSDs is abruptly shut off. Such power failure is often observed in portable devices. For this reason, it is critical to provide a power failure protection scheme for reliable SSDs. In this work, we propose a power-failure protection scheme for SSDs to increase their reliability. The contribution of our work is three-fold. First, we design a power failure protection circuit which incorporates super-capacitors as well as rechargeable batteries. Second, we provide a method to determine the capacity of backup power sources. Third, we propose a data backup procedure when the power failure occurs. We implemented our method on a real board and applied it to a notebook PC with a contemporary SSD. The board measurement and simulation results prove that our method is robust in cases of sudden power failure.

Many simulated annealing algorithms use the Cauchy neighbors for fast convergence, and the conventional method uses the product of n one-dimensional Cauchy distributions as an approximation. However, this method slows down the search severely as the dimension gets high because of the dimension-wise neighbor generation. In this paper, we analyze the orthogonal neighbor characteristics of the conventional method and propose a method of generating symmetric neighbors from the n-dimensional Cauchy distribution. The simulation results show that the proposed method is very effective for the search in the simulated annealing and can be applied to many other stochastic optimization algorithms.

Side match vector quantization (SMVQ) has been originally developed for image compression and is also useful for steganography. SMVQ requires to create its own state codebook for each block in both encoding and decoding phases. Since the conventional method for the state codebook generation is extremely time-consuming, this letter proposes a fast generation method. The proposed method is tens times faster than the conventional one without loss of perceptual visual quality.

This letter proposes a new face sketch recognition method. Given a query sketch and face photos in a database, the proposed method first synthesizes pseudo sketches by computing the locality sensitive histogram and dense illumination invariant features from the resized face photos, then extracts discriminative features by computing histogram of averaged oriented gradients on the query sketch and pseudo sketches, and finally find a match with the shortest cosine distance in the feature space. It achieves accuracy comparable to the state-of-the-art while showing much more robustness than the existing face sketch recognition methods.

This letter proposes a QoS control method for video streaming service over wireless networks. Based on statistical analysis, the time-varying MAC parameters highly related to channel condition are selected to predict available bitrate. Adaptive bitrate control of scalably-encoded video guarantees continuity in streaming service even if the channel condition changes abruptly.

Image deformations caused by different steganographic methods are typically extremely small and highly similar, which makes their detection and identification to be a difficult task. Although recent steganalytic methods using deep learning have achieved high accuracy, they have been made to detect stego images to which specific steganographic methods have been applied. In this letter, a staganalytic method is proposed that uses hierarchical residual neural networks (ResNet), allowing detection (i.e. classification between stego and cover images) and identification of four spatial steganographic methods (i.e. LSB, PVD, WOW and S-UNIWARD). Experimental results show that using hierarchical ResNets achieves a classification rate of 79.71% in quinary classification, which is approximately 23% higher compared to using a plain convolutional neural network (CNN).

We deal with LTI nonminimum phase (NMP) systems which are difficult to control with conventional methods because of their inherent characteristics of undershoot. In such systems, reducing the undesirable undershoot phenomenon makes the response time of the systems much longer. Moreover, it is impossible to control the magnitude of undershoot in a direct way and to predict the response time. In this paper, we propose a novel two sliding mode control scheme which is capable of stably determining the magnitude of undershoot and thus the response time of NMP systems a priori. To do this, we introduce two sliding lines which are in charge of control in turn. One is used to stabilize the system and achieve asymptotic regulation eventually like the conventional sliding mode methods and the other to stably control the magnitude of undershoot from the beginning of control until the state meets the first sliding line. This control scheme will be proved to have an asymptotic regulation property. The computer simulation shows that the proposed control scheme is very effective and suitable for controlling the NMP systems compared with the conventional ones.