Satoru Yamano

An analysis of the channel utilization for call admission control in voice over WLAN

In this paper, we present an analytical method for effectively evaluating the channel utilization of voice calls in voice over WLAN systems. The method is under realistic assumptions general enough to deal with various cases of mixed traffic sources and transmission conditions. The accuracy and effectiveness of our method are validated through experiments. The method provided a basis for a prototype call-admission-control system for VoWLAN, in an attempt to enable an operational VoWLAN system with quality-of-service support.

Link Estimation Methods for Routing over FWA Mesh Network

With the popularity of mobile communication, the importance of backbone network of the mobile networks, i.e. mobile backhaul networks, has increased significantly. With the decreasing size of mobile network system cells, it is considered next-generation mobile backhaul networks will be mesh-based. To reduce the operating expenses, i.e. OPEX, of the network, mobile network carriers are beginning to shift their circuit-switched networks to packet-switched networks. Most mobile backhaul networks are formed with microwave radios. To increase data rate, Adaptive Modulation and Coding (AMC) is used for wireless links. As a result, the data rate of each wireless link changes over time and thus leads to unexpected packet loss or traffic degradation. This paper proposes a routing scheme and methods for estimating the transmission parameters or modes of wireless links to route bandwidth guaranteed flows over mobile backhaul networks. With estimation methods, degradation of existing flows caused by unexpected changes in the data rate of wireless links can be reduced. This paper shows using mode history of link to estimate the link quality can route bandwidth guaranteed flows efficiently by choosing more stable links for the path. We also show that link estimation methods are effective when mode distribution follows normal, uniform and Poisson distributions.

An Autonomous and Distributed Mobility Management Scheme in Mobile Core Networks

The 5th generation mobile and wireless communication systems are expected to accommodate exploding traffic, increasing number of devices, and heterogeneous applications driven by proliferation of IoT and M2M technologies. The centralized mobility management architecture in a current mobile core network cannot satisfy these emerging requirements. In this paper, we introduce novel architecture of distributed mobility management and an autonomous and adaptive mobility management scheme which distributes mobility management function on nodes in a mobile core network in accordance with mobility characteristics of UEs and a management policy. We adopt a biologically-inspired adaptation algorithm, called attractor selection, to accomplish adaptive selection taking into account multiple objectives. Through simulation experiments, we conrmed that our proposal could accomplish lower delay, higher load balancing, and lower C-plane overhead comparing to other methods including the current standard.

On the effectiveness of integrating WiMAX and Wi-Fi

In this paper, we give a quantitative evaluation on the effect of integrating WiMAX and Wi-Fi, as compared to the case of separate WiMAX and Wi-Fi systems, with respect to the system capacity under QoS constraint. We focus particularly on the VoIP traffic aspects of the system. Based on this capacity evaluation, a cost analysis is further presented. We also propose and analyse a resource management scheme on Wi-Fi to WiMAX handover.

High performance network with merged optical and IP

The ubiquitous network is, in a sense, the ultimate goal of communication services. As the desire for ubiquitous network becomes increasingly clear, network service providers are anticipated to develop a high performance network infrastructure for providing larger capacity and more flexible communication services. If such a communication infrastructure can be constructed inexpensively while retaining scalability, it should present a new business opportunity for network service providers. This paper presents a new network infrastructure that merges optics with IP, and then studies how to realize the infrastructure and what the component technologies are. In addition, this paper takes a look at the network elements that comprise an optical-IP merged network and services.

Capacity analysis and resource management of an integrated WiMAX & Wi-Fi access system for VoIP

In this paper, we give a quantitative evaluation on the effect of integrating WiMAX and Wi-Fi, as compared to the case of separate WiMAX and Wi-Fi systems, on the system capacity with QoS being considered. We focus particularly on the VoIP traffic aspects of the system. Based on this capacity evaluation, a cost analysis is further presented. We also propose and analyze a resource management scheme on Wi-Fi to WiMAX handover.