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This paper demonstrates an implemented bandwidth management system for the QoS-assured network architecture. To provide a cost-effective priority service, service providers should utilize the bandwidth in the existing core network. Therefore, the system dynamically optimizes the resource allocation at the edge of the network considering current bandwidth usage along the path in the core network. In...
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...
Heterogeneous wireless access networks will be deployed in many areas. IEEE802.11g and IEEE802.16e will become key technologies as means of providing wireless broadband access to mobile users. These two different wireless access technologies will co-exist while complementing each other in the near future; hence, a mobile node (MN) with dual interfaces will likely execute many handovers (HOs) between...
In the near future, many access points (APs) belonging to different IP subnets will become widespread and thus will be complementarily integrated to cover a wide area. In the wireless environment, common TCP connection-oriented communication has to be maintained when a mobile node (MN) moves across many APs with different IP subnets that causes a change in the IP address of the MN. Furthermore, TCP...
In the near future, wireless local area networks (WLANs) will overlap to provide continuous coverage over a wide area. In such ubiquitous WLANs, a mobile node (MN) freely moves between WLANs with different IP subnets during VoIP communication. However, existing methods cannot sufficiently maintain VoIP quality during handover due to changes of IP address and inappropriate execution of handover. To...
The emerging mobile WiMAX (IEEE 802.16e) has gained serious attention as a means of providing wireless broadband access to mobile users. 802.16e supports high data rates and QoS for various applications, and is thus a powerful contender for next generation wireless access technology. On the other hand, IEEE 802.11 a/b/g/n have already been widely used to provide high data rates in a limited area....
To develop compact and thin antennas at UHF-band, a printed J-shaped monopole array antenna was discussed for reception of terrestrial broadcasting TV signals. This antenna consists of a folded J-shaped lambda/4 monopole antenna array fed by a coplanar waveguide. A simple matching circuit consisting of an open-ended slotted line and high impedance step section were installed between the antenna and...
This paper proposes a network architecture to achieve a QoS assured network, which is composed of two QoS control technologies such as IP flow control and MPLS DiffServ-TE. IP flow control technology is utilized to treat IP packets as an IP flow distinguished by source and destination IP addresses, ports, protocol and priority and to apply the CAC function on the per- flow basis. MPLS DiffServ-TE...
It is important for ubiquitous networks to survey a wireless area with required communication quality, i.e., communication quality required by an application. However, communication quality of wireless networks dynamically changes depending on various invisible factors. Nor can their influence be accurately estimated beforehand. Thus, actual wireless measurement is unavoidable. Existing wireless measurement...
Switching a communication path from one access point (AP) to another in inter-domain WLANs is a critical challenge for delay-sensitive applications such as voice over IP (VoIP) because communication quality during handoff (HO) is more likely to be deteriorated. To maintain VoIP quality during HO, we need to solve many problems. In particular, in bi-directional communication such as VoIP, an AP becomes...
With the spread of small wireless devices, mobile mesh networks (MMN) will be constructed in the near future by interconnecting such devices. However, it is difficult to reliably deliver data over the moving nodes in an MMN due to the instability of the wireless medium and the movement itself of mobile nodes. Although an existing method, MORE, improves the efficiency of data delivery in fixed wireless...
A J-shaped monopole antenna array with matching circuits of a slot transmission line was considered for the purpose of development of compact and thin antennas. The return loss was measured to be about more than 10 dB at UHF band. This performance can guarantee the specification of the digital broadcasting at UHF band, and besides, the size of this J-shaped monopole antenna array is reasonably small...
To miniaturize thin types of printed antennas, a bilaterally-etched cross meander-line antenna was developed for specified low-power radio applications at 300 MHz. This antenna consists of two meander-line patterns etched on both surfaces of a dielectric substrate, where the meander-line patterns were crossed each other. According to analytical results, the return loss of this antenna was 17 dB and...
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...
To miniaturize thin types of printed antennas, a bilaterally-etched cross meander-line antenna was developed for specified low-power radio applications at 300 MHz. This antenna consists of two meander-line patterns etched on both surfaces of a dielectric substrate, where the meander-line patterns were crossed each other. According to analytical results, the return loss of this antenna was 17 dB and...
Providing useful information and services based on a user's context is one of the key factors in achieving a ubiquitous environment. However, it is difficult to obtain a user's context (e.g., temperature and humidity) from a wireless sensor network because the wireless sensor network does not focus on obtaining the requested data from only the closest sensor node. In this paper, we propose a method...
Optical PCE and its interwork with the NMS were investigated for planning and operation of optical transparent networks. We successfully verified effective and fast optical-path computation taking into account the physical impairments and wavelength continuity.
Radiation characteristics of printed slot antennas etched on a high permittivity piece with a relative dielectric constant of 197 were investigated for the purpose of miniaturization of antennas. At first, the effect of shortening of the wavelength caused by use of the high permittivity dielectric material was calculated from the viewpoint of the return loss performance, and it was obvious that the...
In the near future, wireless local area networks (WLANs) will overlap to provide continuous coverage over a wide area. In such ubiquitous WLANs, a mobile node (MN) freely moves between WLANs with different IP subnets during VoIP communication. In such situations, since an MN experiences several handovers, the communication quality is degraded. In previous studies, in order to solve this problem, we...
We propose a data gathering scheme for a wireless sensor network constructed in a building in this paper. Our system consists of gateway nodes that have a power supply and wired connection to a monitoring PC, and sensor nodes that operate on a battery. Sensor information is periodically gathered from all sensor nodes via gateway nodes to a monitoring PC. To conserve energy, the emission of sensor...
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