IEEE 802.15.6 provides PHY and MAC layer profiles for wearable and implanted Wireless Body Area Networks (WBANs). The critical requirements of QoS guarantee and ultra-low-power are severe challenges when implementing IEEE 802.15.6. In this paper, the key problem in IEEE 802.15.6 standard that “How to allocate EAP (Exclusive Access Phase)?” is solved for the first time: An analysis of network performance indicates that too much EAP allocation can not promote traffic performance obviously and effectually. However, since EAP allocation plays an important role in guaranteeing quality of service, a customized and quantitative EAP allocation solution is proposed. Simulation results show that the solution can obtain the optimal network performance. Furthermore, the estimated models of delay and energy are developed, which help to design the WBAN according to application requirements and analyze the network performance according to the traffic characteristics. The models are simple, effective, and relatively accurate. Results show that the models have approximated mean and the correlation coefficient is greater than 0.95 compared with the simulations of IEEE 802.15.6 using NS2 platform. The work of this paper can solve crucial practical problems in using IEEE 802.15.6, and will propel WBANs applications widely.

In this paper, we use neural networks (NNs) for cross-dialectal (Mandarin-Shanghainese) voice conversion using a bi-dialectal speakers' recordings. This system employs a nonlinear mapping function, which is trained by parallel mandarin features of source and target speakers, to convert source speaker's Shanghainese features to those of target speaker. This study investigates three training aspects: a) Frequency warping, which is supposed to be language independent; b) Pre-training, which drives weights to a better starting point than random initialization or be regarded as unsupervised feature learning; and c) Sequence training, which minimizes sequence-level errors and matches objectives used in training and converting. Experimental results show that the performance of cross-dialectal voice conversion is close to that of intra-dialectal. This benefit is likely from the strong learning capabilities of NNs, e.g., exploiting feature correlations between fundamental frequency (F0) and spectrum. The objective measures: log spectral distortion (LSD) and root mean squared error (RMSE) of F0, both show that pre-training and sequence training outperform the frame-level mean square error (MSE) training. The naturalness of the converted Shanghainese speech and the similarity between converted Shanghainese speech and target Mandarin speech are significantly improved.

The dynamic time warping (DTW) algorithm is widely used to determine time series similarity search. As DTW has quadratic time complexity, the time taken for similarity search is the bottleneck for virtually all time series data mining algorithms. In this paper, we present a parallel approach for DTW on a heterogeneous platform with a graphics processing unit (GPU). In order to exploit fine-grained data-level parallelism, we propose a specific parallel decomposition in DTW. Furthermore, we introduce an optimization technique called diamond tiling to improve the utilization of threads. Results show that our approach substantially reduces computational time.

New HEu$_{1-x}$Gd$_{x}$(MoO$_4$)$_2$ nanophosphors were synthesized by a simple one-step ion-exchange method. These nanophosphors have rod-like particle morphology with 0.5--15,$mu$ m in length and outer diameters in the range of 50--500,nm. By optimization of the composition, the highest emission intensity was obtained for the samples with $x = 0.50$ for both KEu$_{1-x}$Gd$_{x}$(MoO$_{4}$)$_{2}$ and HEu$_{1-x}$Gd$_{x}$(MoO$_{4}$)$_{2}$.

In developing an automatic system of a single tooth length measurement on x-ray image, since a tooth shape is assumed to be straight and curve, an algorithm which can accurately deal with straight and curve is required. This paper proposes an automatic algorithm for measuring the length of single straight and curve teeth. In the algorithm consisting of control point determination, curve fitting, and length measurement, PCA is employed to find the first and second principle axes as vertical and horizontal ones of the tooth, and two terminal points of vertical axis and the junction of those axes are determined as three first-order control points. Signature is then used to find a peak representing tooth root apex as the forth control point. Bezier curve, Euclidean distance, and perspective transform are finally applied with determined four control points in curve fitting and tooth length measurement. In the experiment, comparing with the conventional PCA-based method, the average mean square error (MSE) of the line points plotted by the expert is reduced from 7.548 pixels to 4.714 pixels for tooth image type-I, whereas the average MSE value is reduced from 7.713 pixels and 7.877 pixels to 4.809 pixels and 5.253 pixels for left side and right side of tooth image type-H, respectively.

In the impulse noise removal from a color image, vector filters are suitable for suppressing false color generation. However, the vector filters do not select optimal vectors to restore noise corrupted pixels. To cope with this problem, a cost function-based vector filter is proposed in this letter.

Self-aligned four-terminal (4T) planar metal double-gate (DG) polycrystalline-silicon (poly-Si) thin-film transistors (TFTs) were fabricated on a glass substrate at a low temperature (LT), which is below $550^{circ}$C, to realize high performance and low power dissipation system-on-glass (SoG). The top gate (TG) and bottom gate (BG) were formed from tungsten (W); the BG was embedded in the glass substrate and the TG was fabricated by a self-alignment process using the BG as a photomask. This structure is called embedded metal double-gate (E-MeDG) in this paper. The poly-Si channel with lateral large grains was fabricated using a continuous-wave laser lateral crystallization (CLC). The self-aligned 4T E-MeDG LT poly-Si TFT, with a gate length of 5,$mu $m and TG and BG SiO$_2$ thicknesses of 50 and 100,nm, respectively, exhibited a subthreshold swing of 120,mV/dec and a threshold voltage ($mathrm{V}_{mathrm{th}}$) of $-$0.5,V in the connecting DG mode; i.e. when TG is connected to BG. In the TG operation at various BG control voltage, a threshold voltage modulation factor $(gamma = Delta mathrm{V}_{mathrm{th}}/Delta mathrm{V}_{mathrm{BG}})$ of 0.47 at negative BG control voltage and 0.60 at positive BG control voltage are demonstrated, which values are nearly equal to theoretical prediction of 0.40 and 0.75. Trend of subthreshold swing (s.s.) of TG operation under different BG control voltage are also consistent with theoretical prediction. In addition to TG operation, successful BG operation under various TG control voltages was confirmed. Field-effect mobility derived from g$_{mathrm{m}}$ also varied depending on control gate voltage. The high controllability of device parameter of individual LT poly-Si TFTs is caused by excellent crystalline quality of CLC poly-Si film and will enable us to the fabrication of high-speed and low power-dissipation SoG.

Due to limitations of today's widely-deployed commercial networks, some end-user applications are only possible through, or greatly improved by execution on virtualized networks that have been enhanced or idealized in a way which specifically supports the application. This paper describes US Ignite and the advantages provided to US Ignite end-user applications running on virtual networks which variously: (a) minimize latency, (b) minimize jitter, (c) minimize or eliminate packet drops, (d) optimize branch points for multicast packet duplication, (e) provide isolation for sensitive information flows, and/or (f) bundle network billing with application use. Examples of US Ignite applications in these categories are provided.

In this paper, a compression-friendly copyright- and privacy-protected image trading system is proposed. In the image trading system, the copyright of the image and the consumer's privacy is important. In addition, it should preserve existing image compression standards. In the proposed method, for privacy protection, the content provider (CP) multiplies random signs to the discrete wavelet transformed (DWTed) coefficients of an image to generate the visually encrypted image. The proposed visually protected images can be efficiently compressed by using JPEG 2000 which compresses the image in the DWTed domain as well. For copyright protection, the trusted third party (TTP) applies digital fingerprinting to the image in the encrypted domain. While in the conventional system, the amplitude-only image (AOI) which is the inversely transformed amplitude spectra of an image is used for privacy protection. Since, the AOI consists of real numbers, to store and transmit the AOI, it has to be quantized before compression. Therefore, quantization errors cannot be avoided in the conventional system. On the other hand, the proposed method applies the digital fingerprint in the DWTed domain, so clipping errors in decoding the image by the TTP is avoided. In addition, only a seed number which is input to a pseudo random number generator is shared between the CP and the consumer, whereas an extra image is shared in the conventional systems. Experimental results show that the proposed system is efficient in terms of privacy protection, compression performance, quality of fingerprinted images, and correct fingerprint extracting performance.

In this paper, we introduce a parallax barrier system that shows high definition autostereoscopy and holds wide viewing zone. The proposed method creates a 4-view parallax barrier system with full display resolution per view by setting aperture ratio to one quarter and using time-division quadplexing, then applies obtained 4-view to 2-view, so that the viewing zone for each eye becomes wider than that from the conventional methods. We build a prototype with two 120,Hz LCD panels and manage to achieve continuous viewing zone with common head-tracking device involved. However, moire patterns and flickers stand out, which are respectively caused by the identical alignments of the color filters on the overlaid LCD panels and a lack of refresh rate of 240,Hz. We successfully remove the moire patterns by changing the structure of the system and inserting a diffuser. We also reduce the flickers by proposing 1-pixel aperture, while stripe shaped noise due to the lack of refresh rate occurs during a blink or a saccade. The stripe noise can be effectively weakened by applying green and magenta anaglyph to the proposed system, where extra crosstalk takes place since the default RGB color filters on LCD panels share certain ranges of wavelength with each other. Although a trade-off turns out to exist between stripe noise and crosstalk from our comparison experiment, results from different settings all hold acceptable quality and show high practicability of our method. Furthermore, we propose a solution that shows possibility to satisfy both claims, where extra color filters with narrow bandwidths are required.

This paper proposes an adaptive band activity ratio control (ABC) with cascaded energy allocation (CEA) scheme to improve end-to-end spectral efficiency for two-hop amplify-and-forward orthogonal frequency division multiplexing relay systems under transmit energy constraint. Subchannel pairing (SP) based spectrum mapping maps spectral components transmitted over high gain subchannels in the source-to-relay link onto high gain subchannels of the relay-to-destination link to improve the spectral efficiency. However, SP suffers from a frame efficiency reduction due to the notification of information of spectral component order. To compensate for the deficiency of SP, the proposed scheme employs dynamic spectrum control with ABC in which spectral components are mapped onto subchannels having high channel gain in each link, while band activity ratio (BAR) is controlled to an optimal value, which is smaller than 1, so that all spectral components are transmitted over relatively high gain subchannels of the two links. To further improve the performance, energy allocation at the source node and the relay node is serially conducted based on convex optimization, and BAR is controlled to improve discrete-input continuous-output memoryless channel capacity at the relay node. In the proposed scheme, since only information of BAR needs to be notified, the notification overhead is drastically reduced compared to that in SP based spectrum mapping. Numerical analysis confirms that the proposed ABC combined with CEA significantly reduces the required notification overhead while achieving almost the same frame error rate performance compared with the SP based scheme.

In this paper, a real-time medium access control (MAC) protocol based on a coding-black-burst mechanism with low latency and high energy efficiency is proposed for wireless sensor networks. The Black-Burst (BB) mechanism is used to provide real-time access. However, when the traffic load is heavy, BB will cause a lot of energy loss and latency due to its large length. A binary coding mechanism is applied to BB in our coding-black-burst-based protocol to reduce the energy consumption and latency by at least (L-2(log2 L+1)) for L-length BB. The new mechanism also gives priority to the real-time traffic with longer waiting delays to access the channel. The theoretical analysis and simulation results indicate that our protocol provides low end-to-end delay and high energy efficiency for real-time communication.

Network selection is one of the hot issues in the fusion of heterogeneous wireless networks (HWNs). However, most of previous works only consider selecting single-access network, which wastes other available network resources, rarely take account of multi-access. To make full utilization of available coexisted networks, this paper proposes a novel multi-access selection algorithm based on joint utility optimization for users with multi-mode terminals. At first, the algorithm adopts exponential smoothing method (ESM) to get smoothed values of received signal strength (RSS). Then we obtain network joint utility function under the constraints of bandwidth and number of networks, with the consideration of trade-off between network benefit and cost. At last, Lagrange multiplier and dual optimization methods are used to maximize joint utility. Users select multiple networks according to the optimal association matrix of user and network. The simulation results show that the proposed algorithm can optimize network joint utility, improve throughput, effectively reduce vertical handoff number, and ensure Quality of Service (QoS).

In this paper, we design an Unequal Error Protection (UEP) rateless code with special coding graph and apply it to propose a novel HTTP adaptive streaming based on UEP rateless code (HASUR). Our designed UEP rateless code provides high diversity on decoding probability and priority for data in different important level with overhead smaller than 0.27. By adopting this UEP rateless channel coding and scalable video source coding, our HASUR ensures symbols with basic quality to be decoded first to guarantee fluent playback experience. Besides, it also provides multiple layers to ensure the most suitable quality for fluctuant bandwidth and packet loss rate (PLR) without estimating them in advance. We evaluate our HASUR against the alternative solutions. Simulation results show that HASUR provides higher video quality and more adapts to bandwidth and PLR than other two commercial schemes under End-to-End transmission.

The Internet Engineering Task Force (IETF) has been actively standardizing distributed mobility management (DMM) schemes with multiple Mobility Anchors (MAs). Yet, all existing schemes have limitations that preclude the efficient distribution of mobile data traffic, including single point failure problems, heavy tunneling overheads between MAs, and a restrictive traffic distribution for external nodes in a mobility domain. Therefore, this paper proposes an efficient mobility management scheme with a virtual Local Mobility Anchor (vLMA). While the vLMA is designed assuming multiple replicated LMAs for a PMIPv6 domain, it acts virtually as a single LMA for the internal and external nodes in the PMIPv6 domain. Furthermore, the vLMA distributes mobile data traffic using replicated LMAs, and routes packets via a replicated LMA on the optimal routing path. Performance evaluations confirm that the proposed scheme can distribute mobile data traffic more efficiently and reduce the end-to-end packet delay than the Distributed Local Mobility Anchor (DLMA) and the Proxy Mobile IPv6 (PMIPv6).

A fully-integrated double-channel 5-Gb/s/ch 2:1 serializer array is designed and fabricated in a standard 0.18-$mu $m CMOS technology, which can be easily expanded to any even-number-channel array, e.g. 12 channels, by means of arrangement in a parallel manner. Besides two conventional half-rate 2:1 serializers, both phase-locked loop and delay-locked loop techniques are employed locally to deal with the involved clocking-related issues, which make the serializer array self-contained, compact and automatic. The system architecture, circuit and layout designs are discussed and analyzed in detail. The chip occupies a die area of 673,$mu $m$, imes ,$667,$mu $m with a core width of only 450,$mu $m. Measurement results show that it works properly without a need for additional clock channels, reference clocks, off-chip tuning, external components, and so on. From a single supply of 1.8,V, a power of 200,mW is consumed and a single-ended swing of above 300,mV for each channel is achieved.

Amplification characteristics of the signal and the noise in the semiconductor optical amplifier (SOA), without facet mirrors for the intensity modulated light, are theoretically analyzed and experimentally confirmed. We have found that the amplification factor of the temporarily varying intensity component is smaller than that of the continuous wave (CW) component, but increases up to that of the CW component in the high frequency region in the SOA. These properties are very peculiar in the SOA, which is not shown in conventional electronic devices and semiconductor lasers. Therefore, the relative intensity noise (RIN), which is defined as ratio of the square value of the intensity fluctuation to that of the CW power can be improved by the amplification by the SOA. On the other hand, the signal to the noise ratio (S/N ratio) defined for ratio of the square value of the modulated signal power to that of the intensity fluctuation have both cases of the degradation and the improvement by the amplification depending on combination of the modulation and the noise frequencies. Experimental confirmations of these peculiar characteristics are also demonstrated.

In this paper, we investigate unitary precoder design for multiple-input multiple-output (MIMO) multicasting, where multiple common data streams are sent to a group of users. Assuming that zero-forcing decision feedback equalizers (ZF-DFE) are adopted at the receiver side, we can convert the multicast channel into multiple parallel subchannels. To improve the receiving quality of all data streams, we focus on maximizing the minimal signal-to-noise ratio (SNR) of all data streams. To effectively handle this non-convex optimization problem, we first consider the special case of two data streams and derive the closed-form solution of the SNR vectors for both subchannels. Based on these results, a gradient-based iterative algorithm is developed for the proposed precoder design. For the general case, a Givens rotation-based iterative algorithm is proposed, where at each iteration the original problem of unitary precoder design is transformed into a dual-stream subproblem. Hence it can be solved efficiently by the gradient-based iterative algorithm. Finally, simulation results are presented to demonstrate the outstanding performance of the proposed design.

Underlay cognitive radio (CR) permits unlicensed secondary users (SUs) to transmit their own data over the licensed spectrum unless the interference from the SUs on the licensed primary user (PU) exceeds an acceptable level. This paper proposes two generalized interference alignment (IA)-based distributed optimization designs for multiple secondary transceivers in the underlay CR case with channel uncertainty under assumption that the actual channel error norm is below a certain bound. One of the designs is an extension to an existing method and the other one is a new design. In these methods, the precoding and power allocation matrices for each SU are either independently or jointly optimized for imperfect channel knowledge to maximize the secondary rates and to hold the secondary interference on the primary receiver under an acceptable limit that is determined by the primary receiver. Numerical results prove the ability of the proposed methods to support significant secondary rates provided that the PU is protected from extra interference from SUs, even in presence of channel uncertainty.

In this paper, the spatial smoothing (SS) method is extended to the wideband multipath case. By reordering the array input signal and the weight vector, the corresponding covariance matrix of each subarray can be constructed conveniently. Then, a novel wideband beamforming algorithm, based on the SS method (SS-WB), can be achieved by linearly constrained minimum variance (LCMV). Further improvement of the output signal-to-interference-plus-noise ratio (SINR) for SS-WB can be obtained by removing the desired signal in the observed array data with the reconstruction of covariance matrix, which is denoted as wideband beamformer based on modified SS method (MSS-WB). Both proposed algorithms can reduce the desired signal cancellation due to the super decorrelation ability of SS method and MSS-WB can lead to a significantly improved output SINR. The simulations verify their effectiveness in the multipath environment.