Selecting transparently a proper network connection for voice communication will be a fundamental requirement in future multi-mode heterogeneous wireless network. This paper presented a smart session selection (S3) scheme to meet this requirement. Instead of selecting a best access network as in conventional Always Best Connected (ABC) paradigm, S3 enables users to select a best network connection, which consists of source and destination access network pair, to satisfy quality constraint and users' preference. To support S3, we develop a user profile to specify network connection priority. Meanwhile IP multimedia subsystem (IMS) is extended to make smart decision for users. Finally, Analytic Hierarchy Process (AHP) is used to recommend a network connection with assistance of user profile and IMS signaling. An example is illustrated to show that AHP can successfully select a good network connection that fulfills the requirement of users.

The properties of the surface-conduction electron-emitter display (SED) are mainly decided by the surface-conduction electron emitters (SCE), which are normally made from the expensive metal Pd. In this study, we propose to use metal Zn instead of Pd as the emitter material. Both the device electrode and ZnO thin film are deposited by a sputter, and the electron emitters (SCE) are formed by the electro-forming process. The electron emission characteristic is obtained and the luminescence is observed.

Phase noise (PHN) can cause the common phase error (CPE) and the inter-carrier interference (ICI), both of which impair the accurate channel estimation in orthogonal frequency division multiplexing (OFDM) systems. In this letter, we build a new signal model parameterized by the channel impulse response, the CPE and the ICI. Based on this model, we derive the maximum likelihood estimator (MLE) and the minimum mean square error estimator (MMSEE). Simulation results show that the proposed schemes significantly improve the performance of OFDM systems in the presence of PHN.

Data compression is popularly applied to computer systems and communication systems in order to reduce storage size and communication time, respectively. Since large data are used frequently, string matching for such data takes a long time. If the data are compressed, the time gets much longer because decompression is necessary. Long string matching time makes computer virus scan time longer and gives serious influence to the security of data. From this, CPM (Compression Pattern Matching) methods for several compression methods have been proposed. This paper proposes CPM method for PPM which achieves fast virus scan and improves dependability of the compressed data, where PPM is based on a Markov model, uses a context information, and achieves a better compression ratio than BW transform and Ziv-Lempel coding. The proposed method encodes the context information, which is generated in the compression process, and appends the encoded data at the beginning of the compressed data as a header. The proposed method uses only the header information. Computer simulation says that augmentation of the compression ratio is less than 5 percent if the order of the PPM is less than 5 and the source file size is more than 1 M bytes, where order is the maximum length of the context used in PPM compression. String matching time is independent of the source file size and is very short, less than 0.3 micro seconds in the PC used for the simulation.

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.

In this letter, a decision-directed MOE detector with excellent robustness against signature waveform mismatch is proposed for DS-CDMA systems. Both the theoretic analysis and computer simulation results demonstrate that the proposed detector can provide better SINR performance than that of conventional detectors.

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.

We have developed a novel railway signal control system that operates as a distributed system. It consists of a central control unit (called LC) and terminal devices (called FC) that are distributed at the railroad wayside and operate signal devices. The Internet technologies and optical LAN technologies have been used as communication methods between the LC and the FCs. While handling enormous amount of electric cables may cause human errors, the system is expected to reduce troubles of the current signal system at construction works thanks to the Internet technologies. The FC is a distributed terminal device that has its own processor and placed at the railroad wayside to control the field signal devices. The LC is a centralized computer device that has software arranged by the function of the field devices. An optical network system and multiple communication paths between the LC and the FCs realize durable transmissions. Moreover, the assure performance of controls and transmissions have been investigated, and the autonomous distributed signal control system is also discussed as the next steps of the system.

Finite impulse response (FIR) filtering is the most computationally intensive operation in the channelizer of a wireless communication receiver. Higher order FIR channel filters are needed in the channelizer to meet the stringent adjacent channel attenuation specifications of wireless communications standards. The computational cost of FIR filters is dominated by the complexity of the coefficient multipliers. Even though many methods for reducing the complexity of filter multipliers have been proposed in literature, these works focused on lower order filters. This paper presents a coefficient-partitioning-based binary subexpression elimination method for realizing low power FIR filters. We show that the FIR filters implemented using proposed method consume less power and achieve speed improvement compared to existing filter implementations. Design examples of the channel filters employed in the Digital Advanced Mobile Phone System (D-AMPS) and Personal Digital Cellular (PDC) receivers show that the proposed method achieved 23% average reductions of full adder and power consumption and 23.3% reduction of delay over the best existing method. Synthesis results show that the proposed method offers average area reduction of 8% and power reduction of 22% over the best known method in literature.

In this letter, we propose a video traffic model based on a class of stochastic processes, which we call truncated GeoY/G/∞ input processes. Group of picture (GOP) size traces are modeled by truncated GeoY/G/∞ input process with gamma-distributed batch sizes Y and Weibull-like autocorrelation function. With full-length MPEG-4 video traces in QCIF, we run simulations to show that our proposed model estimates packet loss ratios at various traffic loads more accurately than existing modeling methods.

This paper proposes a 12-bit 3.7-MS/s pipelined A/D Converter based on the novel capacitor mismatch calibration technique. The conventional stage is improved to an algorithmic circuit involving charge summing, capacitors' exchange and charge redistribution, simply through introducing some extra switches into the analog circuit. This proposed ADC obtains the linearity beyond the accuracy of the capacitor match and verifies the validity of reducing the nonlinear error from the capacitor mismatch to the second order without additional power dissipation through the novel capacitor mismatch calibration technique. It is processed in 0.5 µm CMOS technology. The transistor-level simulation results show that 72.6 dB SNDR, 78.5 dB SFDR are obtained for a 2 V Vpp 159.144 kHz sine input sampled at 3.7 MS/s. The whole power dissipation of this ADC is 33.4 mW at the power supply of 5 V.

We have previously proposed a diffusion-type flow control mechanism as a solution for severely time-sensitive flow control required for high-speed networks. In this mechanism, each node in a network manages its local traffic flow using the basis of only the local information directly available to it, by using predetermined rules. In addition, the implementation of decision-making at each node can lead to optimal performance for the whole network. Our previous studies show that our flow control mechanism with certain parameter settings works well in high-speed networks. However, to apply this mechanism to actual networks, it is necessary to clarify how to design a parameter in our control mechanism. In this paper, we investigate the range of the parameter and derive its optimal value enabling the diffusion-type flow control to work effectively.

Clustering is indispensable to obtain a general view of series data from a number of data such as gene expression profiles. We propose a novel metric for clustering. The proposed metric automatically normalizes data to minimize a logarithmic scale distance between the data series.

A (k,2)-track layout of a graph G consists of a 2-track assignment of G and an edge k-coloring of G with no monochromatic X-crossing. This paper studies the problem of (k,2)-track layout of bipartite graph subdivisions. Recently V. Dujmovi and D.R. Wood showed that for every integer d ≥ 2, every graph G with n vertices has a (d+1,2)-track layout of a subdivision of G with 4 log d qn(G) +3 division vertices per edge, where qn(G) is the queue number of G. This paper improves their result for the case of bipartite graphs, and shows that for every integer d ≥ 2, every bipartite graph Gm,n has a (d+1,2)-track layout of a subdivision of Gm,n with 2 log d n -1 division vertices per edge, where m and n are numbers of vertices of the partite sets of Gm,n with m ≥ n.

We propose a CMOS image sensor that realizes wide dynamic range imaging and nonlinear representation of I/O characteristics. The proposed image sensor controls the integration time for each pixel based on the brightness distribution of objects. The histogram at the end of the integration is estimated from the early intermediate photodiode values that are read out to an external circuit. Using the estimated histogram, the imaging parameters, which control the integration time pixel-by-pixel, are optimized in the external circuit. According to the imaging parameters, the intermediate photodiode value is compared with the threshold and reset to the starting value depending on the comparison result. These processes repeat several times. At the end of the integration, the photodiode value is reconstructed by using the imaging parameters. Then, wide dynamic range images with adapted I/O characteristics are obtained. We have fabricated a prototype with a size of 6464 pixels using a 0.35-µm 2-poly 4-metal CMOS process. In this paper, we explain the principle of the proposed sensor and discuss the system architecture and its operation. The experimental results obtained using the prototype are also presented, and we verify its effectiveness.

Hybrid FEC/ARQ, which is a mixture of forward error correction (FEC) and automatic repeat request (ARQ), is a well-known technique aiming for packet-loss recovery to guarantee quality of service (QoS) for real-time communications. In this paper, focusing on layered video transmission over wireless network environment, we propose a proactive retransmission scheme for hybrid FEC/ARQ. In the proposed scheme, a receiver host periodically sends probe packets to a sender host in order to check wireless channel state. If the sender host does not receive any probe packet during a pre-specified interval, it regards the wireless channel as being in burst loss state, and it proactively retransmits packets expected to be lost during the burst loss period. The buffer management associated with layered video coding is also taken into consideration. The performance of the proposed scheme is investigated by simulation. Numerical examples show that the proposed scheme transmits packets of the base layer more successfully than the conventional FEC/ARQ.

Autonomous Decentralized Community System (ADCS) makes its basis on offering customized and dynamic services to group of end-users having common preferences at specified time and location. Owing to extreme dynamism in the system caused by rapidly varying user's demands, and severe mobility of users, it is quite difficult to assure timely service provision to all community members. This paper presents autonomous decentralized community system construction by autonomous division and integration technologies to procure service assurance under dynamic situations, without involving significant communication overhead. By adopting the concept of size threshold, the proposed technique continuously maintains the appropriate size of community in constantly and rapidly changing operating environment, to deliver optimal quality of service in terms of response time. The effectiveness of proposed technology has been shown through simulation, which reveals remarkable improvement (up to 29%) in response time.

This paper proposes a combination of novel Received Response (RR) sequence at the transmitter and a Matched Filter-RAKE (MF-RAKE) combining scheme receiver system for the Direct Sequence-Code Division Multiple Access Ultra Wideband (DS-CDMA UWB) multipath channel model. This paper also demonstrates the effectiveness of the RR sequence in Multiple Access Interference (MAI) reduction for the DS-CDMA UWB system. It suggests that by using conventional binary code sequence such as the M sequence or the Gold sequence, there is a possibility of generating extra MAI in the UWB system. Therefore, it is quite difficult to collect the energy efficiently although the RAKE reception method is applied at the receiver. The main purpose of the proposed system is to overcome the performance degradation for UWB transmission due to the occurrence of MAI during multiple accessing in the DS-CDMA UWB system. The proposed system improves the system performance by improving the RAKE reception performance using the RR sequence which can reduce the MAI effect significantly. Simulation results verify that significant improvement can be obtained by the proposed system in the UWB multipath channel models.

In this paper, we consider a collision detection problem of spheres which asks to detect all pairs of colliding spheres in a set of n spheres located in d-dimensional space. We propose a collision detection algorithm for spheres based on slab partitioning technique and a plane sweep method. We derive a theoretical upper bound on the time complexity of the algorithm. Our bound tells that if both the dimension and the maximum ratio of radii of two spheres are bounded, then our algorithm runs in O(n log n + K) time with O(n + K) space, where K denotes the number of pairs of colliding spheres.

A differential LC-VCO that adopts a transformer with asymmetric turns-ratio has been proposed. The asymmetric turns-ratio of the transformer leads to the suppression of the AM to FM conversion which is caused by the 1/f noise of the current source transistor. The analysis of the proposed scheme and the improvement in phase noise compare to conventional CMOS LC-VCOs are described. The transformer used in proposed VCO occupies about 430430 µm2 of silicon area while the inductor in compared conventional VCO does 390390 µm2.