This paper provides an overview of the new tendencies in the subjective assessment of the quality of video for Multimedia applications. New subjective assessment methods are here described together with the description of the new general approaches. Some motivations of these new approaches are also here provided.

This paper reports on a study of the interference effects from 2 types of ultra wideband (UWB) sources on a QPSK transmission system by simulation. The culprit UWB sources were: multi-band orthogonal frequency-division multiple-access (MB-OFDM) and direct-sequence UWB (DS-UWB), which were modeled on the proposal specifications in the IEEE 802.15.3a to standardize high-speed wireless personal area networks. Average bit error rate (BER) degradation of the victim system was evaluated under in-band interference from the UWB signals. The proposed modified equivalent baseband system was employed in the simulation in order to reduce the simulation costs. Interference effects from the UWB sources were also examined under a Rayleigh fading channel.

Research has been actively proposed into how to specify requirements in the upper stream of software development. For example, the main research issues regarding Structured Analysis and Object Oriented Analysis methodologies include requirements elicitation, modeling, and validation of specifications to give a starting point for software development. At the same time, another area of research has emerged that recognizes the importance of guaranteeing requirements quality by goals. As the impact of IT penetrates to mobile devices, information appliances and automobiles, goal oriented requirements engineering (GORE) approaches for performance and safety in embedded systems have been proposed. Non-Functional Requirements (NFRs) such as business strategy, security and privacy, are now being formalized by Requirements Engineering (RE) technologies, because enterprise business is now heavily influenced by IT, for example in e-Business. As IT is fast becoming ubiquitous in society, the importance of Goal Orientation will increase as socio-technology enables visualization of the role of software in social systems. In this paper, we discuss the current states and trends of GORE from the viewpoints of both academia and industry.

The purpose of this research is to propose an effective color metric which can predict the perceptual image quality for Retinex method. In this paper, we first give a brief introduction of three kinds of typical single Retinex methods to improve the color reproduction. And then, we state the process for obtaining the observer rating value from the subjective evaluation experiment performed under the sRGB illumination condition. Next, we introduce the S-CIELAB metric and propose a new metric on the basis of S-CIELAB metric that considers the gazing information. The average S-CIELAB color differences with and without the consideration of gazing information were calculated as the objective image quality measures. The correlations between the observer rating values and the objective image quality measures were calculated. The result shows that all of the average S-CIELAB color differences based on the gazing information are better correlated to the observer rating value than the average S-CIELAB color difference over the whole area. The average S-CIELAB color difference weighted by the gazing frequency over the gazing area shows the strong correlation with the observer rating value.

Optical fiber communications require multiple-access schemes to access a shared channel among multiple users. The coherent ultrashort light pulse code-division multiple-access (CDMA) system is one such scheme, and it also offers asynchronous-access communication. This system usually employs 2-level, i.e., binary, m-sequences as signature codes because of their low correlation. If the number of active users is greater than the length of the m-sequence, i.e., code length, distinct m-sequences are used. However, the distinct 2-level m-sequences do not exhibit low correlation, resulting in performance degradation. We therefore propose a coherent ultrashort light pulse CDMA communication system with distinct 4-level, i.e., quaternary, m-sequences to improve system performance when the number of users is greater than the code length. We created the 4-level m-sequences from 2-level m-sequences, and assess the correlation of the 4-level m-sequences. We also theoretically derive the bit error rate (BER) of the proposed system taking into account multiple-access interference (MAI), beat noise, amplified spontaneous emission (ASE), shot noise, and thermal noise. The numerical results show that BER for distinct 4-level m-sequences is more than an order of magnitude smaller than that for distinct 2-level m-sequences. BER is limited by MAI and beat noise when the power of the received signal is high, otherwise BER is limited by ASE, shot noise, and thermal noise.

The multi-step prediction model based on partial least squares (PLS) is established to predict short-term load series with high embedding dimension in this paper, which refrains from cumulative error with local single-step linear model, and can cope with the multi-collinearity in the reconstructed phase space. In the model, PLS is used to model the dynamic evolution between the phase points and the corresponding future points. With research on the PLS theory, the model algorithm is put forward. Finally, the actual load series are used to test this model, and the results show that the model plays well in chaotic time series prediction, even if the embedding dimension is selected a big value.

An analytical approach using human perception has been applied to the evaluation of the front-of-screen (FOS) quality of liquid crystal displays (LCDs), particularly regarding the regions of luminance nonuniformity called "muras." The accurate and consistent inspection of muras is extremely difficult because muras have various shapes and sizes as well as contrasts. And inspection results tend to depend on inspectors during the LCD manufacturing process. To determine the quantitative scale that shows the evaluation results of mura matching human perceptions, first, we conducted a perception test and clarified the "just noticeable difference" (JND) contrast according to the type of mura. Second, the relationship between the JND contrast of mura and background luminance was investigated. Finally, we proposed a quantitative scale of mura level on the basis of the JND contrasts at various background luminances. In this paper, we describe our research on human perception of muras at various background luminances and an approach to determining the quantitative scale of visible muras.

In this paper, given an integer e and n such that e|n, and a prime p, we propose a method of constructing optimal p2-ary low correlation zone (LCZ) sequence set with parameters (pn-1, pe-1, (pn -1)/(pe -1), 1) from a p-ary sequence of the same length with ideal autocorrelation. The resulting p2-ary LCZ sequence set can be viewed as the generalization of the optimal quaternary LCZ sequence set by Kim, Jang, No, and Chung in respect of the alphabet size. This generalization becomes possible due to a completely new proof comprising any prime p. Under this proof, the quaternary case can be considered as a specific example for p = 2.

The family of Quasi-Additive (QA) algorithms is a natural generalization of the perceptron learning, which is a kind of on-line learning having two parameter vectors: One is an accumulation of input vectors and the other is a weight vector for prediction associated with the former by a nonlinear function. We show that the vectors have a dually-flat structure from the information-geometric point of view, and this representation makes it easier to discuss the convergence properties.

Providing multimedia services with a quality-of-service guarantee in mobile wireless networks presents more challenges due to user's mobility and limited bandwidth resource. In order to provide seamless multimedia services in the next-generation wireless networks, efficient call admission control algorithm must be developed. A novel borrowing-based call admission control policy is proposed in this paper as a solution to support quality-of-service guarantees in the mobile multimedia wireless networks. Based on the existing network conditions, the proposed scheme makes an adaptive decision for bandwidth allocation and call admission by employing attribute-measurement mechanism, dynamic time interval reservation strategy, and service-based borrowing strategy in each base station. We use the dynamically adaptive approaches to reduce the connection-blocking probability and connection-dropping probability, and to increase the bandwidth utilization, while the quality-of-service guarantees can be maintained at a comfortable level for mobile multimedia wireless networks. Extensive simulation results show that our proposed scheme outperforms the previously proposed scheme in terms of connection-blocking probability, connection-dropping probability, and bandwidth utilization, while providing highly satisfying degree of quality-of-service in mobile communication systems.

In this letter, we introduce frequency-domain space-time transmit diversity (STTD) encoding/decoding to orthogonal frequency division multiplexing combined with time division multiplexing (OFDM/TDM) on a frame-by-frame basis (i.e., over several concatenated OFDM signals in the frequency-domain) to achieve both spatial and frequency diversity gains and improve the bit error rate (BER) performance. The theoretical BER performance is evaluated by numerical computation using the derived conditional BER and confirmed by computer simulation.

In future systems beyond IMT-2000, macrocell cellular systems such as the 3G systems and high bandwidth microcell wireless systems such as Wireless LAN will complement one another. Routing in the systems beyond IMT-2000 will support seamless inter- and intra-system handover among the cellular and WLAN systems by maintaining active connections. Under such environments, the time scales of mobility and bandwidth-sharing behavior cannot be easily separated. It is not obvious what fraction of traffic is accommodated by each cellular and WLAN system, i.e. the traffic distribution is unknown. This paper shows the considerable impacts the mobility of users has on the capacities of the systems beyond IMT-2000 with roaming capability between different bit rate systems. Especially, this paper demonstrates that the traffic distribution among different systems is a major factor in defining total network throughput. We also provide an analytical method to determine the traffic distribution based on the theory of queueing networks.

In a typical OFDM system, a time domain equalizer (TEQ) can be used in order to reduce the channel length, allowing for shortening of the Cyclic Prefix (CP). In this paper, a novel TEQ method is proposed for OFDM systems, which can reduce implementation complexity without sacrificing performance. Furthermore, the length of the proposed TEQ may be arbitrary. For time-varying channels, an adaptive method is also developed to track the variation of the optimum TEQ coefficients rather than recomputing inversion of the channel matrix.

This paper proposes a frequency-domain equalizer (FEQ) which utilizes not only guard interval but also redundancy in the frequency domain to eliminate inter-symbol and inter-carrier interferences. The proposed FEQ employs the hybrid criterion, i.e., the zero-forcing (ZF) criterion for compensating desired subcarriers and the minimum mean square error (MMSE) criterion for suppressing interference. The proposed Hybrid-FEQ achieves a good equalization performance, because it can suppress the noise enhancement caused by the ZF criterion with relatively small computational complexity exploiting soft-decision forward error correction (FEC). In this paper, we show its equalization performance and complexity compared with the conventional FEQs.

In current IP-based networks, the application of window-based end-to-end flow control, including TCP, to ensure reliable flows is an essential factor. However, since such a flow control is provided by the end hosts, end-to-end control cannot be applied to decision-making in a time-scale shorter than the round-trip delay. We have previously proposed a diffusion-type flow control mechanism to realize the extremely time sensitive flow control that is required for high-speed networks. In this mechanism, each network node manages its own traffic only on the basis of the local information directly available to it, by using predetermined rules. The implementation of decision-making at each node can lead to optimal performance for the whole network. Our previous studies showed that the mechanism works well, by itself, in high-speed networks. However, to apply this mechanism to actual networks, it needs to be able to coexist with other existing protocols. In this paper, we investigate the performance of diffusion-type flow control coexisting with TCP. We show that diffusion-type flow control can coexist with TCP and the two can be complementary. Then, we show that a combination of both controls achieves higher network performance than TCP alone in high-speed networks.

Compound noun segmentation is a key component for Korean language processing. Supervised approaches require some types of human intervention such as maintaining lexicons, manually segmenting the corpora, or devising heuristic rules. Thus, they suffer from the unknown word problem, and cannot distinguish domain-oriented or corpus-directed segmentation results from the others. These problems can be overcome by unsupervised approaches that employ segmentation clues obtained purely from a raw corpus. However, most unsupervised approaches require tuning of empirical parameters or learning of the statistical dictionary. To develop a tuning-less, learning-free unsupervised segmentation algorithm, this study proposes a pruning-based unsupervised technique that eliminates unhelpful segmentation candidates. In addition, unlike previous unsupervised methods that have relied on purely character-based segmentation clues, this study utilizes word-based segmentation clues. Experimental evaluations show that the pruning scheme is very effective to unsupervised segmentation of Korean compound nouns, and the use of word-based prior knowledge enables better segmentation accuracy. This study also shows that the proposed algorithm performs competitively with or better than other unsupervised methods.

The location information of ubiquitous objects is one of the key issues for context-aware systems. Therefore, several positioning systems to obtain precise location information have been researched. However, they have scalability and flexibility problems because they need completely configured space with a large number of sensors. To avoid the problems, we proposed a self-organizing location estimation method that uses ad hoc networks and Self-Organizing Maps and needs no prepared space with a large number of sensors. But, as in other similar precise localization methods, the proposed method needs advanced distance measurements unavailable to conventional wireless communication systems. In this paper, the self-organizing location estimation method's modification for distance measurement that uses received signal strength available to conventional wireless communication systems but which fluctuates uncertainly, is described and location estimation accuracy with the modified method is shown.

Let A(n, d, w) denote the maximum possible number of code words in binary (n,d,w) constant weight codes. For smaller instances of (n, d, w)s, many improvements have occurred over the decades. However, unknown instances still remain for larger (n, d, w)s (for example, those of n > 30 and d > 10). In this paper, we propose a new class of binary constant weight codes that fill in the remaining blank instances of (n, d, w)s. Specifically, we establish several new non-trivial lower bounds such as 336 for A(64, 12, 8), etc. (listed in Table 2). To obtain these results, we have developed a new systematic technique for construction by means of groups acting on some sets. The new technique is performed by considering a triad (G, Ω, f) := ("Group G," "Set Ω," "Action f on Ω") simultaneously. Our results described in Sect. 3 are obtained by using permutations of the elements of a set that include ∞ homogeneously like the other elements, which play a role to improve their randomness. Specifically, in our examples, we adopt the following model such as (PGL2(Fq), P1(Fq), "linear fractional action of subgroups of PGL2(Fq) on P1(Fq)") as a typical construction model. Moreover, as an application, the essential examples in [7] constructed by using an alternating group are again reconstructed with our new technique of a triad model, after which they are all systematically understood in the context of finite subgroups that act fractionally on a projective space over a finite field.

A new fast and reliable image objective quality evaluation technique is presented in this paper. The proposed method takes image structure into account and uses a low complexity homogeneity measure to evaluate the intensity uniformity of a local region based on high-pass operators. We experimented with monochrome images under different types of distortions. Experimental results indicate that the proposed method provides better consistency with the perceived image quality. It is suitable for real applications to control the processed image quality.

A new compact line equalizer is proposed for backplane serial link applications. The equalizer has two control blocks. The feed-forward swing control block determines the optimal low frequency level and the feedback control block detects signal shapes and decides the high-frequency boosting level of the equalizer. Successful equalization is demonstrated over a 1.5 m long PCB trace at 3.125-Gb/s by the circuit realized with 0.18 µm CMOS process. The circuit occupies only 0.16 mm2 and consumes 20 mW with 1.8 V supply.