In this paper, we propose a multi-stage hybrid scheduling scheme for codebook-based precoding systems, which provides a framework to apply different scheduling criterions at different scheduling stages for selecting user equipment (UEs). Numerical simulation results show that the proposed scheme effectively fills the performance gap between maximum carrier-to-interference (Max C/I) power ratio and Proportional Fairness (PF) methods, and provides an important means at the media access control (MAC) layer to lever between aggregate cellular throughput and geometry-specific per-user fairness, in order to meet the requirements of more precise quality of service (QoS) provision for future mobile communication systems.

Codebook based multiple-input multiple-output (MIMO) precoding can significantly improve the system spectral efficiency with limited feedback and has been accepted as one of the most promising techniques for the Evolved UTRA (E-UTRA). Compared with single-user (SU) MIMO, multi-user (MU) MIMO can further improve the system spectral efficiency due to increased multi-user diversity gain. MU-MIMO is preferred for the case of a large number of users,when the total feedback overhead will become a problem. In order to reduce the feedback overhead, feedback of single channel quality indicator (CQI), e.g. rank 1 CQI, is required in E-UTRA currently. The main challenge is how to obtain CQIs of other ranks at Node B for rank adaptation with single CQI feedback. In this paper, an adaptive CQI update scheme at Node B based on statistical characteristics of CQI of various ranks is proposed. To further increase the accuracy of CQI at Node B for data transmission, an adaptive CQI feedback scheme is then proposed in which single CQI with the rank same as previously scheduled is fed back. Simulation results show that our proposed CQI update scheme can achieve 2.5-5% gain compared with the conventional method with fixed backoff. Moreover, with the proposed adaptive feedback scheme, 20-40% performance gain can be obtained and the performance can approach the upper bound.

We propose a selective detection scheme based on pulse repetition considering both BER (Bit Error Rate) performance and complexity in coherent UWB (Ultra Wide Band) systems. To take system complexity into account, the proposed scheme transmits the UWB signals by pulse repetition at the transmitter, like conventional PRC (Pulse Repetition Coding). However, to effectively improve BER performance of the system, the proposed scheme performs selective detection by estimating the SNR (Signal-to-Noise Ratio) of the received pulse-repeated signal at the UWB receiver.

To guarantee the timely provisioning of QoS to real-time oriented multiparty and distributed computing applications (e.g., video conferencing and grid computing) that require the utilization of time and quantity-related resources, the resource should be reserved in advance. However, this new type of reservation (i.e., advance reservation) may collide with legacy (i.e., immediate) reservations that do not specify their session duration. In this paper, to suggest a balanced solution between sharing pools of resources and the managing of collisions between reservation calls, a revenue-based resource sharing scheme (focusing on the bandwidth) is proposed. The proposed scheme attempts to avoid possible collisions by employing a virtual profile of resources reserved in advance in an effort to achieve enhanced resource utilization. It is shown through NS-2 [22] -based network simulations that the proposed scheme can achieve balanced performance when compared with other schemes, including static resource partitioning and complete resource sharing.

In this paper, the simplified search designs for the stochastic codebook of algebraic code excited linear prediction (ACELP) for ITU-T G.729D speech coder are proposed. By using two search rounds and limiting the search range, the computational complexity of the proposed approach is only 6.25% of the full search method recommended by G.729D. In addition, the computational complexity of proposed approach is only 59% of the global pulse replacement search method recommended by G.729.1. Simulation results show that the coded speech quality evaluated by using the standard subjective and objective quality measurements is with perceptually negligible degradation.

This paper presents an integration architecture of content addressable memory (CAM) and a massive-parallel memory-embedded SIMD matrix for constructing a versatile multimedia processor. The massive-parallel memory-embedded SIMD matrix has 2,048 2-bit processing elements, which are connected by a flexible switching network, and supports 2-bit 2,048-way bit-serial and word-parallel operations with a single command. The SIMD matrix architecture is verified to be a better way for processing the repeated arithmetic operation types in multimedia applications. The proposed architecture, reported in this paper, exploits in addition CAM technology and enables therefore fast pipelined table-lookup coding operations. Since both arithmetic and table-lookup operations execute extremely fast, the proposed novel architecture can realize consequently efficient and versatile multimedia data processing. Evaluation results of the proposed CAM-enhanced massive-parallel SIMD matrix processor for the example of the frequently used JPEG image-compression application show that the necessary clock cycle number can be reduced by 86% in comparison to a conventional mobile DSP architecture. The determined performances in Mpixel/mm2 are factors 3.3 and 4.4 better than with a CAM-less massive-parallel memory-embedded SIMD matrix processor and a conventional mobile DSP, respectively.

In a codebook based precoding MIMO system, the precoding codebook significantly determines the system performance. Consequently, it is crucial to design the precoding codebook, which is related to the channel fading, antenna number, spatial correlation etc. So specific channel conditions correspond to respective optimum codebooks. In this paper, in order to obtain the optimum codebooks, a universal unitary space vector quantization (USVQ) codebook design criterion is provided, which can design the optimum codebooks for various fading and spatial correlated channels with arbitrary antenna configurations. Furthermore, the unitary space K-mean (USK) algorithm is also proposed to generate the USVQ codebook, which is iterative and convergent. Simulations show that the capacities of the precoding MIMO schemes using the USVQ codebooks are very close to those of the ideal precoding cases and outperform those of the schemes using the traditional Grassmannian codebooks and the 3GPP LTE DFT (discrete Fourier transform) codebooks.

In this letter, a codebook based multiuser MIMO precoding scheme is proposed for a space-division multiple access (SDMA) system with limited feedback. Focusing on the case of SDMA systems with two transmit antennas, a precoder codebook design is proposed based on the idea that a precoder inducing larger fluctuations in the signal to interference and noise ratio (SINR) at each link can lead to a larger gain in terms of multiuser diversity. It is shown that the proposed multiuser MIMO precoding outperforms existing multiuser MIMO techniques in terms of the average system throughput.

Using Bloom filters is one of the most popular and efficient lookup methods in P2P networks. A Bloom filter is a representation of data item indices, which achieves small memory requirement by allowing one-sided errors (false positive). In the lookup scheme besed on the Bloom filter, each peer disseminates a Bloom filter representing indices of the data items it owns in advance. Using the information of disseminated Bloom filters as a clue, each query can find a short path to its destination. In this paper, we propose an efficient extension of the Bloom filter, called a Deterministic Decay Bloom Filter (DDBF) and an index dissemination method based on it. While the index dissemination based on a standard Bloom filter suffers performance degradation by containing information of too many data items when its dissemination radius is large, the DDBF can circumvent such degradation by limiting information according to the distance between the filter holder and the items holders, i.e., a DDBF contains less information for faraway items and more information for nearby items. Interestingly, the construction of DDBFs requires no extra cost above that of standard filters. We also show by simulation that our method can achieve better lookup performance than existing ones.

In this study, we conducted a series of experiments using stimuli characterized by various attributes in order to understand the categorization process in an infant's pre-linguistic development. The infants are able to assign the same label to members within the same category by focusing attention on specific features or functions common to the members. The ability to categorize is likely to play an essential role in an infant's overall cognitive development. Specifically, we investigated how the infants use different strategies in the process of linguistic categorization. In one strategy, members of a single category are derived from perceptual similarities within the most representative members, i.e., the prototypical members. Alternatively, each membership is established by referring to the linguistic labels for each category provided by the caretaker, in a symbol grounding process. We found that the infant is able to employ these strategies in a flexible manner in its development. We discuss the interplay between different cognitive strategies, including the prototype effects in the infant's cognitive development and the implications for cortical mechanism involved.

The photo-mask cost of standard-cell-based ASICs has been increased so prohibitively that low-volume production LSIs are difficult to fabricate due to high non-recurring engineering (NRE) cost including mask cost. Recently, user-programmable devices, such as FPGAs are started to be used for low-volume consumer products. However, FPGAs cannot be replaced for general purpose because of its lower speed-performance and higher power consumption. In this paper, we propose the user-programmable architecture called VPEX (Via Programmable logic device using EXclusive-or array), in which the hardware logic can be programmed by changing layout patterns on 2 via-layers. The logic element (LE) of VPEX consists of complex-gate-type EXclusive OR (EXOR) and Inverter (NOT) gates. The single LE can output 12 logics which include NOT, Buffer (BUF), all 2-inputs logic functions, 3-inputs AOI21 and inverted-output multiplexer (MUXI) by changing via-1 layout pattern. Furthermore, via-1 layout is optimized for high-throughput EB direct writing, so mask-less programming will be realized in VPEX. We compared the performance of area, speed, and power consumption of VPEX with that of standard-cell-based ASICs and FPGAs. As a result, the speed performance of VPEX was much better than FPGAs and about 1.3-1.6 times worse than standard-cells. We believe that the combination of VPEX architecture and EB direct writing is the best solution for low-volume production LSIs.

This letter presents low-complexity digital pulse shaping filter structures of a direct sequence code division multiple access (DS-CDMA) ultra wide-band (UWB) modem transmitter with a ternary spreading code. The proposed finite impulse response (FIR) filter structures using a look-up table (LUT) have the effect of saving the amount of memory by about 50% to 80% in comparison to the conventional FIR filter structures, and consequently are suitable for a high-speed parallel data process.

The N-dimensional (N-D) Hilbert curve is a one-to-one mapping between N-D space and one-dimensional (1-D) space. It is studied actively in the area of digital image processing as a scan technique (Hilbert scan) because of its property of preserving the spatial relationship of the N-D patterns. Currently there exist several Hilbert scan algorithms. However, these algorithms have two strict restrictions in implementation. First, recursive functions are used to generate a Hilbert curve, which makes the algorithms complex and computationally expensive. Second, all the sides of the scanned region must have the same size and the length must be a power of two, which limits the application of the Hilbert scan greatly. Thus in order to remove these constraints and improve the Hilbert scan for general application, a nonrecursive N-D Pseudo-Hilbert scan algorithm based on two look-up tables is proposed in this paper. The merit of the proposed algorithm is that implementation is much easier than the original one while preserving the original characteristics. The experimental results indicate that the Pseudo-Hilbert scan can preserve point neighborhoods as much as possible and take advantage of the high correlation between neighboring lattice points, and it also shows the competitive performance of the Pseudo-Hilbert scan in comparison with other common scan techniques. We believe that this novel scan technique undoubtedly leads to many new applications in those areas can benefit from reducing the dimensionality of the problem.

This paper proposes several cepstral statistics compensation and normalization algorithms which alleviate the effect of additive noise on cepstral features for speech recognition. The algorithms are simple yet efficient noise reduction techniques that use online-constructed pseudo-stereo codebooks to evaluate the statistics in both clean and noisy environments. The process yields transformations for both clean speech cepstra and noise-corrupted speech cepstra, or for noise-corrupted speech cepstra only, so that the statistics of the transformed speech cepstra are similar for both environments. Experimental results show that these codebook-based algorithms can provide significant performance gains compared to results obtained by using conventional utterance-based normalization approaches. The proposed codebook-based cesptral mean and variance normalization (C-CMVN), linear least squares (LLS) and quadratic least squares (QLS) outperform utterance-based CMVN (U-CMVN) by 26.03%, 22.72% and 27.48%, respectively, in relative word error rate reduction for experiments conducted on Test Set A of the Aurora-2 digit database.

With advances in ubiquitous environments, user demand for easy data-lookup is growing rapidly. Not only users but intelligent ubiquitous applications also require data-lookup services for a ubiquitous computing framework. This paper proposes a backward-compatible, searchable virtual file system (S-VFS) for easy data-lookup. We add search functionality to the VFS, the de facto standard abstraction layer over the file system. Users can find a file by its attributes without remembering the full path. S-VFS maintains the attributes and the indexing structures in a normal file per partition. It processes queries and returns the results in a form of a virtual directory. S-VFS is the modified VFS, but uses legacy file systems without any modification. Since S-VFS supports full backward compatibility, users can even browse hierarchically with the legacy path name. We implement S-VFS in Linux kernel 2.6.7-21. Experiments with randomly generated queries demonstrate outstanding lookup performance with a small overhead for indexing.

In this paper, we show that speed and yield of reconfigurable devices can be enhanced by utilizing within-die (WID) delay variations. An LUT Array LSI is fabricated to confirm whether FPGAs have clear WID variations to be utilized. We can measure delay variations by counting the number of LUTs a signal propagates within a certain time. Clear die-to-die (D2D) and WID variations are observed. We propose a variation model from the measurement results. Adequacy of the model is discussed from randomness of the random component. Effect of the speed and yield enhancement is confirmed using the proposed model. Yield increases from 80.0% to 100.0% by optimizing configurations.

The 2-dimensional (2-D) Hilbert curve is a one-to-one mapping between 2-D space and one-dimensional (1-D) space. It is studied actively in the area of digital image processing as a scan technique (Hilbert scan) because of its property of preserving the spacial relationship of the 2-D patterns. Currently there exist several Hilbert scan algorithms. However, these algorithms have two strict restrictions in implementation. First, recursive functions are used to generate a Hilbert curve, which makes the algorithms complex and computationally expensive. Second, both sides of the scanned rectangle must have same size and each size must be a power of two, which limits the application of the Hilbert scan greatly. In this paper, a Pseudo-Hilbert scan algorithm based on two look-up tables is proposed. The proposed method improves the Hilbert scan to be suitable for real-time processing and general application. The simulation indicates that the Pseudo-Hilbert scan can preserve point neighborhoods as much as possible and take advantage of the high correlation between neighboring lattice points. It also shows competitive performance of the Pseudo-Hilbert scan in comparison with other scan techniques.

This paper presents a scalable FPGA/ASIC implementation architecture for high-speed parallel table-lookup-coding using multi-ported content addressable memory, aiming at facilitating effective table-lookup-coding solutions. The multi-ported CAM adopts a Flexible Multi-ported Content Addressable Memory (FMCAM) technology, which represents an effective parallel processing architecture and was previously reported in [1]. To achieve a high-speed parallel table-lookup-coding solution, FMCAM is improved by additional schemes for a single search mode and counting value setting mode, so that it permits fast parallel table-lookup-coding operations. Evaluation results for Huffman encoding within the JPEG application show that a synthesized semi-custom ASIC implementation of the proposed architecture can already reduce the required clock-cycle number by 93% in comparison to a conventional DSP. Furthermore, the performance per area unit, measured in MOPS/mm2, can be improved by a factor of 3.8 in comparison to parallel operated DSPs. Consequently, the proposed architecture is very suitable for FPGA/ASIC implementation, and is a promising solution for small area integrated realization of real-time table-lookup-coding applications.

In the field of industrial manufacturing, visual pattern inspection is an important task to prevent the inclusion of incorrect parts. There have been demands for such methods able to handle factors caused by positional and rotational alignment, and illumination changes. In this paper, we propose a discrimination method called Trinarized broad-edge and Gray-scale Hybrid Matching (TGHM). The method is highly reliable due to gray-scale cross correlation which has a high pattern discrimination efficiency, with high-speed position and rotation alignment using the characteristics of trinarized broad-edge representation which has high data compressibility and illumination-resistant variability. In an example in which the method is applied to mis-collation inspection equipment of a bookbinding machine, it is confirmed that the processing speed is 24,000 sheets/hour, the error detection rate is 100.0%, and the mis-alarm rate is less than 0.002%, and it is verified that the method is practical.

Analog-to-Digital converters (ADCs) for video applications have made exciting progress in miniaturization and power reduction in the past 20 years. This paper mainly describes the key technologies for miniaturization and power reduction of 10-bit video-frequency ADCs. By reviewing useful architectures and circuit schemes for video-frequency ADCs, self-calibration techniques and interleaving techniques are surveyed. The subranging pipeline look-ahead ADC architecture is introduced. It has a potential for reducing power consumption and improving conversion rate when minute deep submicron CMOS devices are used with low supply voltage.