In this paper, we describe a new way of mobility support for the Internet and Intranet called "Unified Access." Different from other similar proposed technologies like Mobile IP, our scheme is more easy to use, secure, and have the full backward compatibility with existing equipments which are already used.

Certain relationships between successive packet loss patterns and packet spacing are described. To observe a successive packet loss pattern, one possible method is to investigate test packets that are generated at certain intervals (e. g. , Poisson interval, constant regular interval). However, successive packet loss strongly depends on the interval generated. If test packets are generated with long intervals, then successive loss pattern cannot be shown. Thus, in such a method, where the packet intervals may sometimes be long or short, the successiveness of the packet loss should be considered in terms of the packet spacing. To clarify the relationship between the successive packet loss and the packet spacing, we analyze data based on observation of an actual network with the loss window size as a parameter. We find that when the packet spacing is narrower, i. e. , has a shorter interval, the probability becomes higher that the packet immediately following a single packet loss would also be lost.

This paper proposes a new model which can approximate the delay time distribution in the Internet. It is well known that the delay time in communication links follows the exponential distribution. However, the earlier models cannot explain the distribution when a communication link is heavily overloaded. This paper proposes to use the M/M/S(m) model for the Internet. We have applied our model to the measurement results. This paper deals with one-way delay because it reflects the actual characteristics of communication links. Most measurement statistics in the Internet have been based on round-trip time delay between two end nodes. These characteristics are easily measured by sending sample packets from one node to the other. The receiver side echoes back the packets. However, the results are not always useful. A long distance communication link, such as a leased line, has two different fibers or wires for each direction: an incoming link, and an outgoing link. When the link is overloaded, the traffic in each link is quite different. The measurement of one-way delay is especially important for multimedia communications, because audio and video transmissions are essentially one-way traffic.

We have investigated the operation of a reflection type magnetostatic wave signal-to-noise enhancer in detail. It has good enhancement characteristics, low insertion loss, and low operating power. It is also composed of a transducer using a ceramic substrate having a high dielectric constant and an LaGa-YIG film with low saturation magnetization to enable direct operation in the 400-MHz band (the IF band of current DBS receivers). Enhancement of 8 dB was achieved over a 40-MHz bandwidth. Although its operating frequency range depends critically on device temperature, we can compensate for the temperature dependence by adjusting the bias magnetic field. Experiments showed that the enhancer improved the received carrier-to-noise ratio by 2 to 3 dB, providing good noise reduction in DBS reception.

Label switching technology enables high performance and flexible layer-3 packet forwarding using the fixed length label information mapped to the corresponding layer-3 packet stream. A Label Switching Router (LSR), applying label switching technology, forwards layer-3 packets either by their layer-3 address information or by their label information mapped to the layer-3 address information. In order to apply label switching technology to ATM links, we have introduced a new identifier called a Virtual Connection ID (VCID). The VCID value is shared between the neighboring LSR nodes. This paper proposes a VCID notification procedure and evaluates the performance of LSP (Label Switching Path) establishment with the VCID notification procedure. The prototype system can establish 142.9 LSPs in one second with PVC operation, and 10.53 LSPs in one second with SVC operation. Of the entire LSP establishment procedure, the VCID notification procedure contributes only 3 ms, corresponding to only 3% of the entire LSP establishment procedure with SVC operation. Evaluation using a real traffic trace between Japan and the U. S. shows that the required maximum number for LSP establishment is 17 per second. With SVC operation, the prototype system will not be able to achieve sufficient performance with regard to LSP establishment. Since the contribution by the ATM signaling is large, i. e. , 88 ms (= 92.6%), we need to improve the performance of ATM signaling with SVC operation.

An ATM buffer management scheme with logically separated buffers is proposed to guarantee various Quality of Services such as CBR, rt-VBR, nrt-VBR, ABR, and UBR and to make efficient use of system resources in ATM switching systems. By assigning proper priorities based on the count indicator (CI) and the time indicator (TI), respectively, the scheme can afford ABR services without cell loss and real-time services with controllable delay.

A compact new test structure using shift register circuits for extracting components of the capacitance matrix of the multi-layer interconnections has been proposed. An extraction method of the capacitance matrix is also presented. As a result of fabrication, capacitance values obtained by measurement are in good agreement with the numerical calculation. We also showed an estimation method of the measurement errors.

This paper presents a contact-less connector using proximity coupling through a parasitic element. For example, proximity coupling is used for interconnect of microstrip lines for DC-break structure. We also present a cross wiring structure using this interconnect.

In deep submicron CMOS and BICMOS technologies, antenna effects affect floating gate charge of usual floating gate test structures, dedicated to capacitor matching measurement. In this paper a new pseudo-floating gate test structure is designed. After test structure and modeling presentation, testing method and results are given for several capacitor layouts (poly-poly and metal-metal).

This paper evaluates the performance of a reliable multicast protocol for bulk-data transfer over unreliable networks via IP-multicast. Bulk-data type reliable multicast appears promising for commercial publishing and large-scale data replication. The proposed reliable multicast transport protocol (RMTP) provides high-performance due to the use of IP multicast while also providing confirmed and error free transfer by end-to-end controls. The protocol includes a multi-round selective repeat scheme dedicated for bulk-data multicast applications. This paper examines the multicast retransmission procedures in RMTP through analysis and tests on an implemented system and clarifies the basic performance behavior of the protocol. Evaluations are conducted with regard to retransmission redundancy, transfer time, and packet processing load with various error conditions and number of receivers. Against the response concentration problem seen in end-to-end communication, the backoff time algorithm is applied to the protocol; the limits it places on system scalability are clarified.

This paper proposes a newly developed dual-frequency antenna for 800 MHz and 1500 MHz band use. A uniformly spaced array configuration, originally designed for a 800 MHz analog system, is extended to yield dual frequencies operations. An important characteristic of a base station antenna is low sidelobe level in order to suppress inter-cell interference. In the case of a uniformly spaced array configuration, sidelobe levels are increased by the emergence of grating lobes at higher frequencies. Electrical beam tilt also degrades the sidelobe level. As does the change in the excitation coefficients of the array elements at higher frequencies. These three factors are studied theoretically to yield practical sidelobe levels. One more important beam characteristic is the sector beam in the horizontal plane. The same beam width in two frequency bands is achieved by designing the novel reflector shape and determining the proper array element positions in front of the reflector. Practical antenna characteristics are confirmed by designing, manufacturing, and testing a base station antenna.

Although there are many multimedia presentation systems on the market, they have some shortcomings and most of them only can work on one single computer, and few of them can work on Web. Thus, in the thesis we develop a network multimedia presentation system to let users easily design the multimedia presentation without restriction on technology or presentation time and place. Our system includes 3 main components: User Interface that includes temporal specification editor, spatial specification editor and multimedia object interface, Presentation Interface and Knowledge Base. There is a dynamic homepage generator in our system and we propose a displaying algorithm based on the Allen's theory, that there exist 13 temporal relationships between two intervals, for synchronizing the media objects.

The change over from IPv4 to IPv6 entails a potential increase in the number of records that the Registry System must maintain. Currently, only a few Network Information Centers (NICs), controlled by Internet Assigned Number Authority (IANA), operate their Registry Systems. As they concentrates data into several Registry System, it is not scalable. This paper focuses on the scalability issue in a Registry System and Mie Advanced Registry System (MARS) is proposed. Through the collaboration of independent Registry Systems, MARS ensures data consistency as well as making it possible to access data managed by other Registry Systems. A prototype system of MARS is implemented, maintained and managed on the WIDE 6bone. Some lessen from the operation of MARS give also described.

This paper shows the applicability of the integral equation formulation of the measured equation of invariance (IE-MEI) to two-dimensional dielectric scatterers. That is, a relationship between the scattered electric and magnetic fields, which is derived from the new formulation of the IE-MEI, is applicable to lossless dielectric materials as well as perfect electric conductors (PEC). In addition, we show that the IE-MEI does not suffer from internal resonance problems. These two facts are validated by numerical examples for a circular cylinder and a square cylinder illuminated by Transverse Magnetic (TM) plane wave or a TM line source very close to the scatterers. The numerical results calculated by the IE-MEI agree well with the ones by moment methods that employ combined field formulations with exact boundary conditions.

An advanced characterization method for sub-micron DRAM cell transistors has been proposed for the analysis of transistor test structures using memory cell patterns. When the actual memory cell layout is used as a test structure, the parasitic source and drain resistance of the test structure affected conventional transistor parameters such as threshold voltage. To solve this problem, reduced drain current measurement methods have been proposed to suppress the parasitic resistance voltage drop. In these measurements, two new transistor parameters, Vgoff and Vgsat, have been proposed which are related to off-leakage and full writing, respectively. These parameters are found to be good parameters for monitoring DRAM bit failures. A new threshold voltage measurement methodology has also been proposed for test structures with high parasitic resistance.

The effect of lot size change and test processing logistics on VLSI manufacturing final test process efficiency and cost due to the transition of from conventional 5 or 6 inches to 300 mm (12 inches) in wafer size is evaluated through simulation analysis. Simulated results show that a high test efficiency and a low test cost are maintained regardless of arrival lot size in the range of the number of 300 mm wafers per lot from 1 to 25 and the content of express lots in the range of up to 50% by using WEIGHT+RPM rule and the right final test processing logistics. WEIGHT+RPM rule is the rule that considers the jig and temperature exchanging time, the lot waiting time in queue and also the remaining processing time of the machine in use. The logistics has a small processing and moving lot size equal to the batch size of testing equipment.

A novel method of extraction of emitter, Re, and base, Rb, resistances of bipolar junction transistors, BJTs, is proposed. Re and Rb are obtained from static characteristics and noise power spectral density of low frequency, 1/f, fluctuations, measured in the base and collector currents of the devices. Measurements carried out on quasi self-aligned silicon BJTs show that Re and Rb values obtained by the proposed method scale correctly with transistor dimensions and match the values estimated from the device layout.

Congestion Control Scheme of TCP/IP protocol suite is established by Transmission Control Protocol (TCP). Using the self-clocking scheme, TCP is able to maintain a quick optimum connection status for the network path, unless it is given an excessive load to carry to the network. However, in wide area networks, there are some obstructive factors for the self-clocking scheme of TCP. In this paper, we describe the obstructive factors for the self-clocking scheme. We propose a new congestion control scheme using a packet pair scheme and a traffic-shaping scheme. In combining these schemes with TCP, new TCP options and a modification for TCP congestion control algorithms are added. Using our scheme, TCP is able to maintain smooth self-clocking. We implemented this scheme on a network simulator for evaluation. Compared with normal TCP, this scheme was demonstrated to be over 20% more efficient in symmetric communication and over 40% more efficient in asymmetric communication.

In this paper, an adaptive method for active control of vibration intensity in the frequency domain is proposed. In this method, vibration intensity is observed with the 4-sensor method, and the coefficients of an adaptive FIR filter for the active control is renewed with the Block Filtered-X LMS algorithm in the frequency domain. An experiment with the proposed method is performed on a simple model. As a result, the proposed method gives larger attenuation of vibration intensity than the conventional method in the high frequency region. The overall attenuation in vibration intensity in that frequency region is 14.1 dB with the proposed method, while it is 7.0 dB with the conventional method. In the lower frequency region, the reduction in vibration intensity by the proposed method is roughly equivalent to that obtained by the conventional method. An improvement may also be achieved there by setting the intervals between error sensors properly.

In this paper, the correlation properties are used to develop two efficient encoding schemes for speech line spectrum frequency (LSF) parameters. The first scheme (1D KL), which exploits the intraframe correlation, is based on one-dimensional Karhunen-Loeve (KL) transformation; the second scheme, which requires some coding delays to further utilize the interframe correlation, uses two-dimensional (2D KL) transform in the frequency domain or one-dimensional KL transform co-operating with DPCM in the time domain. Moreover, since the KL transform is globally optimal, which is sensitive to the change of input data statistics, further two adaptive transform coding systems are also investigated in this paper. The performance of all systems for different bit rates is investigated and adequate comparisons are made. It is shown that the gain of using KL transformation to exploit the intraframe and interframe correlation is 3 and 4 bits/speech frame, respectively.