Reiji Aibara

A seamless handoff for dual-interfaced mobile devices in hybrid wireless access networks

Todays wireless access networks consist of several overlapping tiers. Provision of real time undisrupted communication to mobile users, anywhere and anytime through these heterogeneous overlay networks, is a challenging task. This paper presents a handoff technique for mobile devices equipped with dual mode interfaces. The proposed mobile-controlled handoff scheme reduces the service disruption time during both horizontal as well as vertical handoffs. We exploit the IP diversity created by the dual interfaces in the overlapping area by simultaneously connecting to different subnets or networks. Power saving is achieved by activating both interfaces only during the handoff period. The analysis shows that with proper network engineering, the service disruption during handoff can be reduced significantly by exploiting the overlapping area between subnets. With more powerful network interfaces, our proposal of dual interfaces can be realized.

Dynamic LoD for QoS management in the next generation VRML

A high speed computer network will provide us with new broadband multimedia applications. This paper discusses new functions for the next generation VRML (Virtual Reality Modeling Language) over high speed computer networks. The LoD (Level of Detail) of 3D objects is the most important function for rendering scenes dynamically while managing the QoS (Quality of Service). New requirements for the next generation VRML are discussed. We present Differential VRML (DVRML) in order to update scene graphs dynamically, and describe principles of the LoD function based on the DVRML.

Efficient fair queueing for ATM networks using uniform round robin

In this paper, we investigate scheduling algorithms that are suitable for ATM networks. In ATM networks, all packets have a fixed small length of 53 bytes and they are transmitted at very high rate. Therefore a time complexity of a scheduling algorithm is quite important. Most scheduling algorithms proposed so far have a complexity of O(log N) per packet, where N denotes the number of connections sharing the link. In contrast, weighted round robin(WRR) has the advantage of having O(1) complexity; however, it is known that its delay property gets worse as N increases, To solve this problem, in this paper we propose two new variants of WRR, uniform round robin (URR) and idling uniform round robin (I-URR). Both disciplines provide end-to-end delay and fairness bounds which are independent of N. Complexity of URR, however, slightly increases as N increases, while I-URR has complexity of O(1) per packet. I-URR also works as a traffic shaper, so that it can significantly alleviate congestion on the network. We also introduce a hierarchical WRR discipline (H-WRR) which consists of different WRR servers using I-URR as the root server. H-WRR efficiently accommodates both guaranteed and best-effort connections, while maintaining O(1) complexity per packet. If several connections are reserving the same bandwidth, their delay bounds achieved by H-WRR are close to those of weighted fair queueing.

MAT: an end-to-end mobile communication architecture with seamless IP handoff support for the next generation internet

The technological advancement in the area of handheld mobile devices has resulted in a movement towards total mobility. Real-time applications are demanding such a flexible mobility support that would not interact adversely with the existing protocols, especially with Quality of Service (QoS) and security mechanisms. We believe that this could be achieved by providing mobility services through the mobile nodes themselves rather than via proxies. This paper proposes an end-to-end mobile communication architecture, called Mobile IP with Address Translation (MAT). MAT does not require any modification in the core network. To realize mobility we use address translation within host-nodes at the IP layer. We describe MAT architecture and show its mobility capability by prototype implementation and evaluation. Preliminary results show that MAT is fully compatible and works fine in both IPv4 and IPv6 environment. We also compare its features with Mobile IPv4 (MIP), Mobile IPv6 (MIPv6) and Location Independent Network Architecture (LIN6) protocols. Furthermore we propose a handoff technique based on MAT which helps to reduce service disruption interval significantly.

Real-time camera control for videoconferencing over the Internet

In videoconferencing, which means a small group meeting, interactive distance learning and so on, there is a requirement to get required video at a remote site freely and easily by local control of a remote camera. However, there are some delays between camera control operations at a remote site and actual video images displayed on a local screen. Delays are caused by network delays between sender and receiver and by video compression delays. To operate a remote camera interactively, a user must control the device considering these delays. We describe these problems in the case of videoconferencing and develop a real time camera control system to solve them. Our approach does not involve reducing delays but showing delays for users by some indication under the current environment. With our proposed system, a user can easily operate a remote camera without considering network and compression delays. We use a new camera control protocol designed by us in our system. We also describe a prototype system and its evaluation used in distance learning.

Programmable real-time scheduler using a neurocomputer

In real-time systems, the scheduling plays an important role to carry out all tasks within predefined time frames. The scheduling problem, however, is known to be intractable, that is, NP-hard or NP-complete for most cases (Garey and Johnson 1979). In this paper, one of the neural computation techniques is introduced to solve it within a limited time under the hard real-time environment, instead of improving algorithms on conventional computers. Although the neural computation can be realized on a multiprocessor, a special hardware using neural networks is designed to obtain the schedule results without overhead.

A Mobility Management System for the Global Live Migration of Virtual Machine across Multiple Sites

With rapid spread of virtualization technologies, Live migration which provides the ability to migrate a running virtual machine (VM) among physical hosts without interruption. Especially, Global Live Migration (GLM) which enables to migrate VM across the geographically-distributed Wide Area Networks (WANs) is an essential step towards development of the inter-cloud environment. However, GLM gets a bit complicated for network configuration compared with ordinary live migration. We have already proposed the GLM method which implements IP mobility support architecture with multiple interfaces to enable live migration among distributed sites consisting of different IP network segments. However, there is no sufficient consideration about the management of smooth handoff for the VM migration on the Internet. In this paper, we propose a mobility management system for GLM, and integrate into our developed nation-wide virtualization infrastructure. The proposed system enables VMs seamless handoff without any modification of the hypervisor while keeping network configuration of the migrating site. Performance evaluation shows the processing overhead of the proposed management system with GLM among multiple sites which are more than 600 km distant. As a result, we confirm that the proposed system provides smooth handoff for the VM on the widely-distributed environment if the proposed system is implemented.

A template matching algorithm using optically-connected 3-D VLSI architecture

Three-dimensional VLSI (in short, 3-D VLSI) is a new device technology that is expected to realize high performance systems. In this paper, we propose an image processing architecture based on 3-D VLSI consisting of optically-connected layers. Since the optical inter-layer connection seems to have some of useful functions due to isotropic radiation of the light, we algebraicly formulate them as the picture processing operators. Moreover, we show that the operators are available for applications such as template matching. The availability of a proposed template matching algorithm is verified by simulation.

Real-time multimedia network system using VLIW hardware stack processor

We propose a multimedia network system using VLIW hardware stack processors, which supports mainly the presentation layer of OSI protocol and fits various real-time applications including intelligent processing.<<ETX>>

DESIGN OF OPTICALLY COUPLED THREE-DIMENSIONAL CONTENT ADDRESSABLE MEMORY

An optically coupled three-dimensional content addressable memory is newly proposed and an example of parallel data processing systems with this memory is described. The new memory employs the optically coupling flip-flop with LEDs and photoconductors for optical data transfer. The optically coupling flip-flop is optimized in design for achieving a high data transfer rate. Simultaneous data inspection through several memory layers can be implemented by using the optically coupled three-dimensional content addressable memory.