Kazuya Tsukamoto - Academia.edu (original) (raw)

Papers by Kazuya Tsukamoto

2011 IEEE Vehicular Technology Conference (VTC Fall), 2011

... Chikara Yoshimura†, Youhei Fujii†, Kota Nishida†, Kazuya Tsukamoto††, Masato Tsuru††, Yuji Oi... more ... Chikara Yoshimura†, Youhei Fujii†, Kota Nishida†, Kazuya Tsukamoto††, Masato Tsuru††, Yuji Oie†† Department of Computer Science and Electronics Kyushu Institute of Technology Fukuoka, Japan Email: †{chikara , fujii , nishida}@infonet.cse.kyutech.ac.jp ††{ tsukamoto ...

Future vehicular communications systems are expected to utilize the vacant channels (white spaces... more Future vehicular communications systems are expected to utilize the vacant channels (white spaces) of the spectrum, otherwise allocated for specific designated use. One such candidate of white space comes from the TV broadcast band. In this demonstration, we will first present animated results of a TV spectrum measurement campaign along the entire portion of Interstate I-90 located in the US state of Massachusetts. Next, we will demonstrate a cyber-physical proof-of-concept lab implementation of our previously developed control and data channel assignment schemes for vehicle-to-vehicle communications over (TV) white space. Finally we will show a video of actual vehicle to vehicle communications field tests conducted in Japan using TV white space.

Currently, a dedicated frequency band is assigned to each of a number of wireless technologies, a... more Currently, a dedicated frequency band is assigned to each of a number of wireless technologies, artificially causing spectrum shortage for new services. It is expected that cognitive radio technology, which can adaptively detect spatial and temporal changes in use over various frequencies, will facilitate achieving efficient wireless resource sharing. However, in ad hoc cognitive communications, such as vehicle-to-vehicle (V2V) communication, since the existence of a common control channel cannot be assumed due to a lack of infrastructure, distributed channel coordination is invariably needed. As a preliminary step toward cognitive wireless V2V communication, in this paper, we focus on one-hop V2V communication and propose a distributed channel coordination scheme that exploits the different characteristics of various frequencies, in terms of both the data transmission rate and the range. Furthermore, in order to evaluate the effectiveness of the proposed scheme, we develop a channel utilization model in which the utilization of each channel changes temporally and spatially due to both primary (licensed) and secondary (unlicensed, opportunistic) usage. The simulation results demonstrate that the proposed scheme can reliably utilize unused frequency(-ies), even under temporal and spatial changes.

ABSTRACT Vehicular networking has significant potential to enable diverse range of applications, ... more ABSTRACT Vehicular networking has significant potential to enable diverse range of applications, including safety and convenience. As the number of vehicles and applications using the specially designated wireless spectrum grow, one can expect substantial increase in the bandwidth requirements. In this paper and demonstration, we advocate that dynamic spectrum access techniques facilitating the utilization of white spaces for vehicles will be the first step towards solving the expected spectrum shortage. In the demonstration, we will introduce field tests of a multi-hop inter-vehicle communication system with distributed and autonomous TV white space channel selection, performed in Japan from January to February 2012. Furthermore, in addition to the field test videos, we will show an indoor emulation of the entire system used during the field tests in the vehicles.

2015 10th International Conference on P2P, Parallel, Grid, Cloud and Internet Computing (3PGCIC), 2015

2014 23rd International Conference on Computer Communication and Networks (ICCCN), 2014

2014 Ninth International Conference on P2P, Parallel, Grid, Cloud and Internet Computing, 2014

IEICE Communications Express, 2014

2010 Fourth IEEE International Conference on Self-Adaptive and Self-Organizing Systems Workshop, 2010

ABSTRACT We propose a method for self-configuration of wireless access points (APs) that is inspi... more ABSTRACT We propose a method for self-configuration of wireless access points (APs) that is inspired by mechanisms of biological development and evolution. The purpose of the proposed configuration is to simultaneously achieve power savings in the APs and achieve reliable connection services through the APs. The configuration target is the cycle time at which each AP enters the power-off state, which is referred to as the sleep cycle time. Biological development mechanisms form bodies of a variety of shapes using different genomes as design information, and these genomes are modified evolutionarily. Similarly, in the present study, a method inspired by biological development forms a variety of the sleep cycle times of APs, and an evolutionary method modifies the parameter values of the method inspired by the biological development in order to obtain better configurations of the APs. In addition, the regulation method is able to configure APs in a distributed manner without knowing global information, the total number of APs, their locations, or their identifiers, which is actually suitable for the situation assumed in the present study, in which APs are established and removed freely by their owners and AP users freely appear. Simulation results suggest that the proposed method is able to achieve power savings and reliable connection services under several assumptions.

2008 IEEE International Conference on Wireless and Mobile Computing, Networking and Communications, 2008

ABSTRACT In the near future, mobile nodes (MNs) need to automatically select an optimal interface... more ABSTRACT In the near future, mobile nodes (MNs) need to automatically select an optimal interface based on communication quality in a multimodal environment, that is, multimodal communication. While the existing handover management schemes avoid the communication termination, they can not satisfy (1) seamless communication and (2) selection of an optimal wireless network based on communication quality, and thus its performance during handover is drastically decreased. In our previous work, we proposed a new handover management scheme that employs (a) cross-layer approach and (b) multiple TCP connections to satisfy (1) and (2), and showed its effectiveness through simulation experiments. However, any other existing studies have not yet proposed a handover management scheme that employs both (a) cross-layer approach by exploiting beacon messages and (b) multiple TCP connections, and demonstrated the effectiveness of them on a real system. Thus, in this paper, we describe the implementation design of our proposed scheme in detail, and then show preliminary results for the fundamental performance of the proposed prototype system in a real wireless environment.

2014 17th International Conference on Network-Based Information Systems, 2014

2009 6th IEEE Consumer Communications and Networking Conference, 2009

ABSTRACT In this paper, we focus on the problem of tracking a moving target in a wireless sensor ... more ABSTRACT In this paper, we focus on the problem of tracking a moving target in a wireless sensor network (WSN) in which the capability of each sensor is relatively limited in order to construct large-scale WSNs at a reasonable price. In our prior study, we proposed a simple multi-point surveillance scheme for a moving target in a WSN and demonstrated that the scheme achieved high tracking probability with low power consumption. However, we have not suggested guidelines for designing the WSN to completely satisfy the wide range of user requirements. Therefore, in this study, we examine the relationship between tracking probability and sensor density through simulations, and then derive an approximate expression representing the relationship. As a result, we show guidelines for sensor density, tracking probability, and the number of monitoring sensors that satisfy a variety of application demands.

2011 Proceedings of 20th International Conference on Computer Communications and Networks (ICCCN), 2011

ABSTRACT The present paper proposes a self-adaptive routing method for temporary information shar... more ABSTRACT The present paper proposes a self-adaptive routing method for temporary information sharing in a wireless mesh network without a global connection that is deployed in a geographically limited area. The temporary information sharing indicates that for the case in which information senders and receivers freely appear in the network, information is forwarded from an information sender to a receiver. The self-adaptive routing method determines a unique route by operations among numerical values assigned to each node and adaptively changes the assigned numerical values according to the routing results. A variety of types of operations and numerical values can be used for this routing method. In simulations, the method is evaluated in terms of routing reliability under an appearance pattern of an information sender-receiver pair in which a location of the receiver is fixed. Simulation results reveal that routing reliability depends on the types of operations and numerical values and is related to how frequently a closed route is generated in the routing. The results also suggest that the degree of randomness in routing is important for reliable routing and varies with the types of operations and numerical values. Index Terms—wireless mesh network; routing; adaptability; operations; free identifier

Ieice Transactions on Communications, Apr 1, 2008

In ubiquitous networks based on Wireless Local Area Networks (WLANs) with limited individual cove... more In ubiquitous networks based on Wireless Local Area Networks (WLANs) with limited individual coverage, mobile nodes will be likely to traverse different WLANs during TCP communication. An effective handover management scheme for achieving seamless and efficient communication throughout the handover operation is therefore crucial. To achieve this, the following three requirements are essential: (i) early initiation of handover, (ii) elimination of communication interruption upon handover, (iii) selection of an optimal WLAN. The handover scheme proposed in this study employs frame retransmission over WLAN as an indicator of link degradation, and a handover manager (HM) on the transport layer obtains the number of frame retransmissions on the MAC layer using a cross-layer architecture in order to achieve (i) and (iii). Then, it also employs multi-homing in order to achieve (ii). Simulations demonstrate that the proposed scheme can satisfy all of the three requirements and is capable of maintaining TCP performance throughout the handover operation.

Ieice Transactions on Communications, 2006

ABSTRACT Two congestion control schemes designed specifically to handle changes in the datalink i... more ABSTRACT Two congestion control schemes designed specifically to handle changes in the datalink interface of a mobile host are presented. The future mobile environment is expected to involve multimode connectivity to the Internet and dynamic switching of the connection mode depending on network conditions. The conventional Transmission Control Protocol (TCP), however, is unable to maintain stable and efficient throughput across such interface changes. The two main issues are the handling of the change in host Internet Protocol (IP) address, and the reliability and continuity of TCP flow when the datalink interface changes. Although existing architectures addressing the first issue have already been proposed, the problem of congestion control remains. In this paper, considering a large change in bandwidth when the datalink interface changes, two new schemes to address these issues are proposed. The first scheme, Immediate Expiration of Timeout Timer, detects interface changes and begins retransmission immediately without waiting for a retransmission timeout as in existing architectures. The second scheme, Bandwidth-Aware Slow Start Threshold, detects the interface change and estimates the new bandwidth so as to set an appropriate slow start threshold for retransmission. Through simulations, the proposed schemes are demonstrated to provide marked improvements in performance over existing architectures.

Proceedings of the 8th International Conference on Advances in Mobile Computing and Multimedia - MoMM '10, 2010

ABSTRACT In ubiquitous Wireless LANs (WLANs), Mobile Nodes (MNs) are likely to experience many an... more ABSTRACT In ubiquitous Wireless LANs (WLANs), Mobile Nodes (MNs) are likely to experience many and frequent handovers between WLANs managed by different organizations/ISPs during TCP communication. Although we proposed a WLAN handover management scheme based on the number of frame retransmissions, the proposed scheme cannot adapt to multirate WLAN used in a more realistic environment. Furthermore, the handover is controlled based on only a predetermined threshold of the number of frame retransmissions, thereby degrading the performance drastically when the inappropriate threshold is employed. Therefore, in this paper, to enhance the practicality of handover scheme in a realistic environment where WLAN supports multiple data rates and automatically changes the rate in response to wireless link condition, we propose a handover management scheme adaptable to multi-rate WLANs. Our scheme exploits two sorts of information to recognize the wireless condition appropriately: (1) data rate used most frequently (DRMF) by each interface and (2) frame retransmission ratio (FRR) on each interface for some duration. The former of two criteria first enables us to estimate an area where we should start handover, and if DRMFs of two interfaces are same in the area, the latter then allows us to compare wireless condition on two interfaces precisely, thereby giving an optimal handover point. The simulation results demonstrate the advantages of the proposed method, especially in the multi-rate WLAN environment.

Proceedings of the second international workshop on Mobility management & wireless access protocols - MobiWac '04, 2004

A mobility management scheme for handling seamless handoffs between appropriate datalink interfac... more A mobility management scheme for handling seamless handoffs between appropriate datalink interfaces is presented. The future mobile environment will be characterized by multimodal connectivity to the Internet with dynamic switching based on many factors. Many technologies have been proposed to support host mobility across diverse wireless access networks, and operate in various layers of the network architecture. Our major concern is the transport protocol that recovers packets lost during handoffs and controls transmission speed to achieve efficient communication. In this paper, we first examine the various latencies associated with the handoff mechanism, and discuss the limited performance of existing technologies based on a single transport connection. We then propose a new mobility management scheme that resolves the problems of limited performance by transport protocol supporting multiple connections. We compare the performance of the proposed scheme with existing technologies, and demonstrate that the proposed scheme achieves excellent goodput performance.

IDPs have been synthesized under microgravity. The morphology and the chemical composition were s... more IDPs have been synthesized under microgravity. The morphology and the chemical composition were studied by TEM, the result of which is similar to natural one. In situ measurement of temperature and the concentration around the melt was also employed