A DFT-Based method (DBM) has been proposed to compensate for the performance degradation caused by clipping distortion at the expense of bandwidth expansion. On the other hand, in any communication systems, conventional channel coding methods can be employed to improve performance. In this letter, the performance of the DBM and the channel coding methods (CCM) are compared. Furthermore, we introduce a hybrid system which outperforms both the DBM and the CCM.

In this paper, a novel Wold decomposition algorithm is proposed to address the issue of deterministic component extraction for texture images. This algorithm exploits the wavelet-based singularity detection theory to process both harmonic a nd evanescent features from frequency domain. This exploitation is based on the 2D Lebesgue decomposition theory. When applying multiresolution analysis techniq ue to the power spectrum density (PSD) of a regular homogeneous random field, its indeterministic component will be effectively smoothed, and its deterministic component will remain dominant at coarse scale. By means of propagating these positions to the finest scale, the deterministic component can be properly extracted. From experiment, the proposed algorithm can obtain results that satisfactorily ensure its robustness and efficiency.

This paper analyzes the voice packet dropping probability and the average message transmission delay of a Bluetooth radio link in which talkspurts and messages are simultaneously transmitted as voice packets and data packets over an SCO (Synchronous Connection-Oriented) link and an ACL (Asynchronous ConnectionLess) link, respectively. The behaviors of an SCO link and an ACL link are modeled using Markov processes. Using these two Markov models and EPA (Equilibrium Point Analysis), the voice packet dropping probability and the average message transmission delay are derived analytically in terms of the permission probability of a voice packet and a data packet, the length of a message, the number of slaves, and the arrival rate of the messages. Some numerical examples are given to show how the permission probabilities, the number of slaves and other parameters influence the transmission delay, when both the SCO link and the ACL link are used at the same time.

A major challenge in the design of multimedia networks is to meet the quality of service (QoS) requirements of all admitted users. Regulation and scheduling are key factors for fulfilling such requirements. We propose a rate-based regulation-scheduling scheme in which the regulation function is modulated by both the tagged stream's characteristics and the state information fed-back from the scheduler. The rate-jitter and bandwidth share of each tagged connection are controlled appropriately by considering the system time and the queue length of the scheduler. Simulation results have shown that the proposed scheme works better than other rate-based disciplines.

Traceback schemes used in Viterbi decoders can be categorized into multi-pointer and one-pointer methods. A traceback scheme using one-pointer method has been shown to be better than the one using multi-pointer method in terms of memory size and latency. We propose an area efficient traceback method which is based on the one-pointer scheme. The proposed method can be implemented by using only two single-port memory banks. In comparison with traditional methods, lower power consumption and smaller area occupation are required for the proposed method.

We developed a compact, 16-channel integrated optical subscriber module for one-fiber bi-directional optical access systems. They can support more subscribers in a limited mounting space. For ultimate compactness, we created 8-channel integrated super-compact optical modules, 4-channel integrated limiting amplifiers, and 4-channel integrated LD drivers for Fast Ethernet. We introduce a new simulation method to analyze the electrical crosstalk that degrades sensitivity of the optical module. A new IC architecture is applied to reduce electrical crosstalk. We manufactured the optical subscriber module with these optical modules and ICs. Experiments confirm that the module offers a sensitivity of -27.3 dBm under 16-channel 125 Mbit/s simultaneous operation.

In this letter, we propose a groupwise successive interference cancellation (GSIC) receiver with gradient descent search for multi-rate DS-CDMA system. Proposed receiver incorporates iterative gradient descent search algorithm into conventional GSIC receiver for multi-rate DS-CDMA system. It is shown that the receiver achieves significant performance improvement over the matched filter (MF) receiver, GSIC receiver, multi-stage parallel interference cacnellation (PIC) receiver, multi-stage partial PIC receiver, and GSIC receiver with PIC in a Rayleigh fading channel.

The classification time required by conventional multi-class SVMs greatly increases as the number of pattern classes increases. This is due to the fact that the needed set of binary class SVMs gets quite large. In this paper, we propose a method to reduce the number of classes by using nearest neighbor rule (NNR) in the principle component analysis and linear discriminant analysis (PCA+LDA) feature subspace. The proposed method reduces the number of face classes by selecting a few classes closest to the test data projected in the PCA+LDA feature subspace. Results of experiment show that our proposed method has a lower error rate than nearest neighbor classification (NNC) method. Though our error rate is comparable to the conventional multi-class SVMs, the classification process of our method is much faster.

In this paper, we design and implement a fast asynchronous embedded CISC microprocessor, A8051, introducing well-tuned pipeline architecture and enhanced control schemes. This work shows an asynchronous design methodology for a CISC type processor, handling the complicated control structure and various instructions. We tuned the proposed architecture to the 5-stage pipeline, reducing the number of idle stages. For the work, we regrouped the instructions based on the number of the machine cycles identified. A8051 has three enhanced control features to improve the system performance: multi-looping control of the pipeline stage, variable length instruction register to get a multiple word instruction in a time, and branch prediction accelerating. The proposed A8051 was synthesized to a gate level design using a 0.35 µm CMOS standard cell library. Simulation results indicate that A8051 provides about 18 times higher speed than the traditional Intel 8051 and about 5 times higher speed than the previously designed asynchronous 8051. In power consumption, core of A8051 shows 15 times higher MIPS/Watt than the synchronous H8051.

Scenarios that describe concrete situations of software operation play an important role in software development and especially in requirements engineering. Scenario details should vary in content when described from different viewpoints, but this presents a difficulty, because an informal scenario from one viewpoint can not easily be transformed into a scenario from another viewpoint with consistency and assurance. This paper describes (1) a language for describing scenarios in which simple action traces are embellished to include typed frames based on a simple case grammar of actions, and (2) a method to accomplish the transformation between scenarios from different viewpoints based on the scenario description language.

Goal-oriented analysis and use case analysis are well known requirements analysis methods and are putting into practice. Roughly speaking, goal-oriented methods are suitable for eliciting constraints to a system and use case analysis methods elicit concrete system behavior. Thus these methods are complementary and their integration into a new method allows us to get a more powerful requirements elicitation method. This paper proposes a new method where both of the methods are amalgamated. In our method, constraints to the system are refined by goal-oriented style, while system behavior are described with hierarchical use cases. Since a use case is made relate to goals during our elicitation processes, the decomposition of goals and use cases are complementally supported. Furthermore we applied our method to a couple of development projects and assessed its effectiveness.

Mining generalized frequent patterns of generalized association rules is an important process in knowledge discovery system. In this paper, we propose a new approach for efficiently mining all frequent patterns using a novel set enumeration algorithm with two types of constraints on two generalized itemset relationships, called subset-superset and ancestor-descendant constraints. We also show a method to mine a smaller set of generalized closed frequent itemsets instead of mining a large set of conventional generalized frequent itemsets. To this end, we develop two algorithms called SET and cSET for mining generalized frequent itemsets and generalized closed frequent itemsets, respectively. By a number of experiments, the proposed algorithms outperform the previous well-known algorithms in both computational time and memory utilization. Furthermore, the experiments with real datasets indicate that mining generalized closed frequent itemsets gains more merit on computational costs since the number of generalized closed frequent itemsets is much more smaller than the number of generalized frequent itemsets.

The descriptional complexity of iterative arrays (IAs) is studied. Iterative arrays are a parallel computational model with a sequential processing of the input. It is shown that IAs when compared to deterministic finite automata or pushdown automata may provide savings in size which are not bounded by any recursive function, so-called non-recursive trade-offs. Additional non-recursive trade-offs are proven to exist between IAs working in linear time and IAs working in real time. Furthermore, the descriptional complexity of IAs is compared with cellular automata (CAs) and non-recursive trade-offs are proven between two restricted classes. Finally, it is shown that many decidability questions for IAs are undecidable and not semidecidable.

We present an overview of our work on the application of scanning near-field optical microscopy (SNOM) to photonic crystal structures. Our results show that SNOM can be used to map the subwavelength confinement of light to a point-defect in a 2D photonic crystal microresonator. Comparison with numerical modelling shows that SNOM is able to resolve patterns in the intensity distribution that are due to the slight non-uniformity in the crystal structure. We also discuss the future possibilities for applications of different modes of SNOM to photonic crystal devices.

Measuring and modeling network traffic is of key importance for the traffic engineering of IP networks, due to the growing diversity of multimedia applications and the need to efficiently support QoS differentiation in the network. Several recent measurements have shown that Internet traffic may incorporate long-range dependence and self-similar characteristics, which can have significant impact on network performance. Self-similar traffic shows variability over many time scales, and this behavior must be taken into account for accurate prediction of network performance. In this paper, we propose a new parameter fitting procedure for a superposition of Markov Modulated Poisson Processes (MMPPs), which is able to capture self-similarity over a range of time scales. The fitting procedure matches the complete distribution of the arrival process at each time scale of interest. We evaluate the procedure by comparing the Hurst parameter, the probability mass function at each time scale, and the queuing behavior (as assessed by the loss probability and average waiting time), corresponding to measured traffic traces and to traces synthesized according to the proposed model. We consider three measured traffic traces, all exhibiting self-similar behavior: the well-known pOct Bellcore trace, a trace of aggregated IP WAN traffic, and a trace corresponding to the popular file sharing application Kazaa. Our results show that the proposed fitting procedure is able to match closely the distribution over the time scales present in data, leading to an accurate prediction of the queuing behavior.

In future mobile networks, new technologies will be needed to enable a mobile host to move across heterogeneous wireless access networks without disruption of the connection. In the past, many researchers have studied handover in such IP networks. In almost all cases, special network devices are needed to maintain the host's mobility. Moreover, a host cannot move across heterogeneous wireless access networks without degradation of the goodput for real-time communication, although a mobile host with multiple network interfaces can connect to multiple wireless access networks. For these reasons, we consider that a mobile host needs to manage seamless handover on an end-to-end basis. In this paper, we propose a multi-path transmission algorithm for end-to-end seamless handover. The main purpose of this algorithm is to improve the goodput during handover by sending the same packets along multiple paths, minimizing unnecessary consumption of network resources. We evaluate our algorithm through simulations and show that a mobile host gains a better goodput.

In this paper, we propose a preemptive test scheduling technique (a test can be interrupted and later resumed) for core-based systems with the objective to minimize the test application time. We make use of reconfigurable core test wrappers in order to increase the flexibility in the scheduling process. The advantage with such a wrapper is that it is not limited to a single TAM (test access mechanism) bandwidth (wrapper chain configuration) at each core. We model the scheduling problem as a Bin-packing problem, and we discuss the transformation: number of TAM wires (wrapper-chains) versus test time in combination with preemption, as well as the possibilities and the limitations to achieve an optimal solution in respect to test application time. We have implemented the proposed preemptive test scheduling algorithm, and we have through experiments demonstrated its efficiency.

As semiconductor manufacturing technology advances, power dissipation and noise in scan testing have become critical problems. Our studies on practical LSI manufacturing show that power supply voltage drop causes testing problems during shift operations in scan testing. In this paper, we present a new testing method named MD-SCAN (Multi-Duty SCAN) which solves power supply voltage drop problems, as well as its experimental results applied to practical LSI chips.

We suggest to use short secret keys in the anonymous group identification scheme proposed by Lee, Deng, and Zhu and prove that this scheme is secure under the discrete logarithm with short exponents assumption that solving the discrete logarithm problem modulo an n-bit prime p is hard even when the exponent is a small c-bit number. We show that the communication and the computation costs are lower than those of the Lee-Deng-Zhu scheme.

Fast algorithms for computing the running type-I discrete sine transform (DST-I) and type-III discrete sine transform (DST-III) are proposed. The algorithms are based on a recursive relationship between three subsequent local discrete sine spectra. The computational complexity of the algorithms is compared with that of fast DST-I and DST-III algorithms. Fast inverse algorithms for signal processing in the running discrete sine transform domains are also proposed.