To meet the bandwidth requirements of multimedia services, multipath transmission is a promising solution. In this paper, we consider multi-access networks, where WiMAX and WiFi links are set up at the same time. Multipath transmission suffers from the intrinsic problem of out-of-order packet delivery. This has an adverse impact on TCP and even UDP-based delay sensitive applications. However, multimedia streaming services allow some tolerance to transmission delay. Motivated by this observation, we investigate how to split multimedia flows over heterogeneous links. Wireless link capacity varies widely over time due to dynamic radio conditions. The capacity variations should be promptly reflected in traffic splitting in order to accomplish an equal load-balance. A practical prototype system has been implemented. We have performed extensive measurements from a prototype system. Through practical experimental results, we could verify two major research goals. One is that multimedia splitting can improve the overall network performance (e.g., the permitted multimedia sessions or the aggregated bandwidth) while still keeping an acceptable media quality. The other is an adaptation capability to varying link quality. It has been widely investigated under various radio conditions and different monitoring intervals. It is shown that the adaptive technique is effective under dynamic radio environments.

The performance of the ordered successive interference cancellation (OSIC) signal detection method is well known to depend on the successful detection of the first layer. In a previous work, in an effort to mitigate the error propagation effect, all the constellation points were tried as the first layer symbol, thereby achieving a better performance. In this letter, we show that the selection of the first layer impacts the error performance significantly, and based on the observation, we propose a novel signal detection method QR-LRL. In the proposed work, the least reliable layer (LRL) is chosen to be the first layer, which is shown to be the best choice in terms of noise enhancement in detecting the other layers. Also, we discuss Log Likelihood Ratio (LLR) computation when the proposed method is used. Computer simulations confirm the efficacy of the proposed method.

In H.264/AVC standard, many new techniques such as variable block size (VBS) and multiple reference frame (MRF) are used in motion estimation (ME) part to achieve superior coding performance. However, the use of new techniques will also cause great burden on computation complexity, which leads to problems in low power hardware implementation. Many software based fast ME algorithms are proposed to reduce complexity. For real-time hardwired encoder, the huge throughput of fractional motion estimation (FME) and integer motion estimation (IME) makes pipeline stage a must. In this case, IME is arranged in a single stage, which deteriorates the efficiency of many software based algorithms. Based on the hardware data flow, this paper provides a complexity reduction algorithm which speeds up ME procedure through three schemes. Firstly, the proposed algorithm executes similarity analysis to detect big mode MB and apply early termination in IME stage. Secondly, for normal MB, motion feature is extracted after IME of each frame and a 6-ring based search range adjustment scheme is introduced to remove redundant search positions. Thirdly, for MBs which have large motion feature, the pixel difference is very small due to the blur effect on video sensor. So, we use subsampling technique to reduce computation complexity for such MBs. Experimental results show that, compared with hardware friendly full search algorithm, the proposed fast ME algorithm can reduce 52.63% to 83.21% ME time with negligible video quality degradation. Furthermore, since the proposed algorithm works in a hardware friendly way, it can be embedded into 3-stage real-time hardwired video encoder to achieve low power design.

With the nano-scale technology, an system-on-chip (SOC) design may consist of many reusable cores from multiple sources. This causes that the complexity of SOC testing is much higher than that of conventional VLSI chip testing. One of the SOC test challenges is the test data reduction. This paper presents a multi-code compression (MCC) technique to reduce the volume of test data and the test application time. A multi-code decompressor for recovering the compressed test data is also proposed. Experimental results show that the MCC scheme can achieve higher compression ratio than single-code compression schemes. The area cost of the proposed multi-code decompressor is small--only about 3498 µm2 based on TSMC 0.18 µm standard cell technology.

In this paper, we propose an image completion algorithm which takes advantage of the countless number of images available on Internet photo sharing sites to replace occlusions in an input image. The algorithm 1) automatically selects the most suitable images from a database of downloaded images and 2) seamlessly completes the input image using the selected images with minimal user intervention. Experimental results on input images captured at various locations and scene conditions demonstrate the effectiveness of the proposed technique in seamlessly reconstructing user-defined occlusions.

In 2003, Kobayashi et al. proposed a new class of knapsack public-key cryptosystems over Gaussian integer ring. This scheme using two-sequences as the public key. In 2005, Sakamoto and Hayashi proposed an improved version of Kobayashi's scheme. In this paper, we propose the knapsack PKC using l-sequences as the public key and present the low-density attack on it. We have described Schemes R and G for l=2, in which the public keys are constructed over rational integer ring and over Gaussian integer ring, respectively. We discusses on the difference of the security against the low-density attack. We show that the security levels of Schemes R and G differ only slightly.

In this paper, we propose a method that uses Simulated Annealing (SA) to estimate the linear and nonlinear parameters of a closed-box loudspeaker system for implementing effective Mirror filters. The nonlinear parameters determined by W. Klippel's method are sometimes inaccurate and imaginary. In contrast, the proposed method can estimate the parameters with satisfactory accuracy due to its use of SA; the resulting impedance and displacement characteristics match those of an actual equivalent loudspeaker. A Mirror filter designed around these parameters can well compensate the nonlinear distortions of the loudspeaker system. Experiments demonstrate that the method can reduce the levels of nonlinear distortion by 5 dB to 20 dB compared to the before compensation condition.

In wireless ad hoc networks, providing an authentication service to verify that the broadcast packet is from the claimed sender without modification, is challenging due mainly to the inherently lossy wireless links. This paper presents a novel Secure and Reliable Broadcasting that reinforces the broadcast authentication with reliability and energy-efficiency capabilities by using the cooperative diversity to superimpose two distinct signals. The proposed protocol achieves significant savings of transmission power and fair assurance of reliability among receivers.

This letter presents an efficient adaptive beamformer to deal with the multipath environments created by signal source scatterings. To improve the performance possible with the fixed forgetting factor, the regular adaptive forgetting factor algorithm is derived and applied to the subarray recursive least squares (RLS) beamforming. Simulations confirm that the proposed scheme has better performance than not only the conventional RLS algorithm but also the subarray RLS and adaptive forgetting factor RLS algorithms.

This paper gives a survey and comparison of algorithms for the detection of binary data in the presence of two-dimensional (2-D) intersymbol interference. This is a general problem of communication theory, because it can be applied to various practical problems in data storage and transmission. Major results on trellis-based detection algorithms, previously disparate are drawn together, and placed into a common framework. All algorithms have better complexity than optimal detection, and complexity is compared. On the one hand, many algorithms perform within 1.0 dB or better of optimal performance. On the other hand, none of these proposed algorithms can find the optimal solution at high SNR, which is surprising. Extensive discussion outlines further open problems.

In this paper, we proposed a novel entropy-based image watermarking method in wavelet domain. Unlike traditional entropy, we use the normalized energy instead of the probability which is called energy-based entropy (EBE). Based on EBE, the watermark can be embedded robustly and imperceptibly. In our proposed method, the wavelet-trees are grouped into super-trees. Then each super-tree is also divided into five sub-blocks. According to the watermark bit state, the EBE of each sub-block will be modified respectively. In an experiment, three images (Lenna, Goldhill and Peppers) are chosen for evaluating the performance. The PSNR of these watermarked images are 44.039, 43.51 and 43.67. Compared with Wang et al.[18], it greatly increases the PSNR, by about 5.8, 4.8 and 3.9 dB respectively. For the consideration of the capacity for embedding, the maximum number of watermark bits is also increased. The experimental results show that the proposed entropy-based watermarking method performs well in JPEG compression, filtering (Gaussian filter, median filter and sharpen) and geometrical attacks (pixel shift and rotation). In addition, it is also very robust to against the multiple watermark attack.

We present the first demonstration of multiple-stage wavelength conversion using cascaded LiNbO3 Mach-Zehnder SSB modulators. Wavelength is accurately shifted by 18 GHz at each stage. 72 GHz frequency shift with the relative intensity noise (RIN) value of -144.5 dB/Hz is achieved by four stages. The achieved equivalent noise figure is 7.5 dB.

This letter addresses the problem of robust transceiver design for the multiuser multiple-input-multiple-output (MIMO) downlink where the channel state information at the base station (BS) is imperfect. A stochastic approach which minimizes the expectation of the total mean square error (MSE) of the downlink conditioned on the channel estimates under a total transmit power constraint is adopted. The iterative algorithm reported in [2] is improved to handle the proposed robust optimization problem. Simulation results show that our proposed robust scheme effectively reduces the performance loss due to channel uncertainties and outperforms existing methods, especially when the channel errors of the users are different.

Electrical characteristics of the mechanically flexible driver LSI as thin as 35 µm mounted directly on a flexible display panel were precisely analyzed. The high-voltage transistors on this LSI show the current decrease by 10-30% in high voltage region, comparing with that of an ordinary thickness LSI. These phenomena can be associated with a self-heating effect. We considered the thermal diffusion on the thin chip by changing material of the measurement stage. Moreover, we analyzed the transistor characteristics on the thin chip under convex and concave bending conditions. The drain current change by piezoresistive effect was observed.

A total-field/scattered-field (TF/SF) boundary which is commonly used in the finite-difference time-domain (FDTD) method to illuminate scatterers by plane waves, is developed for use in the constrained interpolation profile (CIP) method. By taking the numerical dispersion into account, the nearly perfect TF/SF boundary can be achieved, which allows us to calculate incident fields containing high frequency components without fictitious scattered fields. First of all, we formulate the TF/SF boundary in the CIP scheme. The numerical dispersion relation is then reviewed. Finally the numerical dispersion is implemented in the TF/SF boundary to estimate deformed incident fields. The performance of the nearly perfect TF/SF boundary is examined by measuring leaked fields in the SF region, and the proposed method drastically diminish the leakage compared with the simple TF/SF boundary.

Crosstalk delay within an on-chip bus can induce severe transmission performance penalties. The Bus-grouping Asynchronous Transmission (BAT) scheme is proposed to mitigate the performance degradation. Furthermore, considering the distinct spatial locality of transition distribution on some types of buses, we use the locality to optimize the BAT. In terms of the implementation, we propose the Differential Counter Cluster (DCC) synchronous mechanism to synchronize the data transmission, and the Delay Active Shielding (DAS) to protect some critical signals from crosstalk and optimize the routing area overhead. The BAT is scalable with the variation of bus width with little extra implementation complexity. The effectiveness of the BAT is evaluated by focusing on the on-chip buses of a superscalar microprocessor simulator using the SPEC CPU2000 benchmarks. When applied to a 64-bit on-chip instruction bus, the BAT scheme, compared with the conservative approach, Codec and Variable Cycle Transmission (DYN) approaches, improves performance by 55+%, 10+%, 30+%, respectively, at the expense of 13% routing area overhead.

Rapid advances in semiconductor manufacturing technology have led to higher chip power densities, which places greater emphasis on packaging and temperature control during testing. For system-on-chips, peak power-based scheduling algorithms have been used to optimize tests under specified power constraints. However, imposing power constraints does not always solve the problem of overheating due to the non-uniform distribution of power across the chip. This paper presents a TAM/Wrapper co-design methodology for system-on-chips that ensures thermal safety while still optimizing the test schedule. The method combines a simplified thermal-cost model with a traditional bin-packing algorithm to minimize test time while satisfying temperature constraints. Furthermore, for temperature checking, thermal simulation is done using cycle-accurate power profiles for more realistic results. Experiments show that even a minimal sacrifice in test time can yield a considerable decrease in test temperature as well as the possibility of further lowering temperatures beyond those achieved using traditional power-based test scheduling.

Automatic adjustment methods for efficient, precise positioning and release of a virtual 3D object by direct hand manipulation in an immersive virtual reality environment are described and evaluated. The proposed methods are release adjustment, position adjustment, viewpoint adjustment, and virtual hand size adjustment. Combining these methods enables users to manipulate a virtual object efficiently and precisely. An experimental evaluation showed that these methods were effective and useful in terms of the number of task completions and the subjective preference, particularly for a small virtual target.

Liquid crystal (LC) lenses that have hole-patterned electrodes and are driven by two voltages used as imaging devices are reported. Two different LC lenses are applied in image formation systems. One LC lens is used with a polarizer in a relay lens scope, and another LC lens that is polarization independent is used in a TV lens. Both LC lenses play roles of focusing elements in lens systems; objects are separately brought into focus by the LC lenses. Very sharp black-and-white and color images are formed by the systems.

The development of network technology reveals the clear trend that mobile devices will soon be equipped with more and more network-based functions and services. This increase also results in more intrusions and attacks on mobile devices; therefore, mobile security mechanisms are becoming indispensable. In this paper, we propose a novel signature matching scheme for mobile security. This scheme not only emphasizes a small resource requirement and an optimal scan speed, which are both important for resource-limited mobile devices, but also focuses on practical features such as stable performance, fast signature set updates and hardware implementation. This scheme is based on the finite state machine (FSM) approach widely used for string matching. An SRAM-based two-level finite state machine (TFSM) solution is introduced to utilize the unbalanced transition distribution in the original FSM to decrease the memory requirement, and to shorten the critical path of the single-FSM solution. By adjusting the boundary of the two FSMs, optimum memory usage and throughput are obtainable. The hardware circuit of our scheme is designed and evaluated by both FPGA and ASIC technology. The result of FPGA evaluation shows that 2,168 unique patterns with a total of 32,776 characters are stored in 177.75 KB SelectRAM blocks of Xilinx XC4VLX40 FPGA and a 3.0 Gbps throughput is achieved. The result of ASIC evaluation with 180 nm-CMOS library shows a throughput of over 4.5 Gbps with 132 KB of SRAM. Because of the small amount of memory and logic cell requirements, as well as the scalability of our scheme, higher performance is achieved by instantiating several signature matching engines when more resources are provided.