Yudai Honma

A New Multi-Path Routing Methodology Based on Logit Type Assignment

We present a new multi-path routing methodology called MLB-routing based on multinomial logit model, which is well known as the random utility theory. The key concept of the study is to incorporate multiple paths from same origin to desti- nation, and distribute packets followed by the multinomial logit type probability. Since MLB-routing is pure multi-path routing, it reduce the severe convergence to same links and increases the bandwidth utilization in the network. Compared to the existing multi-path routing schemes that select pre-determined alternate paths, the proposed method can dynamically distribute packets to every possible paths and thus is more efficient than them. Furthermore, it should be mentioned that this methodology could be implemented as both link-state protocol and distance-vector protocol. Therefore, it has enough affinity for present Internet mechanism. Using simulations, we have also shown that this methodology produces more efficient use of network and causes significant improvements in end-to-end delays and jitter times. I. INTRODUCTION

Accuracy improvement of CoMPACT monitor by using new probing method

CoMPACT monitor that we have proposed is new technique to measure per-flow quality of service (QoS). CoMPACT monitor provide scalable measurement of one-way delay distribution by the combination of active and passive measurement. Recently, a new probing method for improving the accuracy of simple active measurement have been proposed. In this paper, we adopt the new probing method as active measurement of CoMPACT monitor, and show that the combination improves the accuracy of measurement remarkably for UDP flows.

Optimal Airline Networks, Flight Volumes, and the Number of Crafts for New Low-Cost Carrier in Japan

Recently, numerous low-cost carriers (LCCs) have been established and have become popular as a new style of airline service. In Japan, Peach Aviation began business as an LCC in 2012. However, while it is true that some airline companies are suffering from a slump in business, Peach Aviation has succeeded because it set up a hub airport at Kansai International Airport and runs many cash-cow routes. To establish a new LCC, consideration of airline networks is most important for success. Therefore, in this study, we propose a mathematical model to optimize the airline network, flight volume, and number of aircrafts for maximizing a new LCC’s profit supposing a hub-spoke style network, and solve the model as a mathematical programming problem. First, we investigate the case of a single-hub network, and subsequently consider a two-hub network. It was determined that, when both Narita and Kansai International Airports are chosen as hub airports, a new LCC’s profit is maximized.

Unified Model of Communication Frequency between Users in Social Networks

Our previous studies revealed the structure of social networks, which are behind communication networks, by using various metrics of a communication service (amount of traffic, the number of users, etc.). Moreover, we proposed a communication frequency model between users based on a social network structure, and showed that it can reproduce the growth in the number of social networking service (SNS) users. However, when traffic is generated by this communication frequency model, the volume of traffic is inconsistent with the traffic data used in the social network analysis. In this paper, to resolve this contradiction, we propose a unified communication frequency model between users.

Verification of Accuracy Improvement for CoMPACT Monitor Due to Suboptimal Inter-probe Time

CoMPACT monitor gives the one-way delay distribution of a target flow by using a transformation of one-way delay data obtained by active measurement. The transformation can be determined from passively monitored traffic data for the target flow of the measurement. In a recent study, it was reported that by using an inter-probe time that has a Gamma distribution can improve the accuracy of simple active measurement. In this study, we show that CoMPACT monitor is improved in accuracy by the application of new active measurement.

Design of Probe Intervals to Improve Accuracy of CoMPACT Monitor

We have proposed CoMPACT monitor that achieves scalable measurement of one-way delay distribution for each flow. CoMPACT monitor is technique that transforms one-way delay data obtained by active measurement by using passively monitored traffic data of the target flow. In a recent study, it was reported that by using an inter-probe time that has a Gamma distribution can improve the accuracy of simple active measurement. The improvement is in terms of the ensemble mean of stationary stochastic process. In this paper, to improve accuracy of CoMPACT monitor, we apply Gamma-probing as an active measurement of CoMPACT monitor. The significant issue in this application is in the difference between objects to measure; CoMPACT monitor estimates not the ensemble mean but the time average of sample path. We investigate the characteristics of CoMPACT monitor and Gamma-probing, and verify the accuracy improvement of CoMPACT monitor through simulations.

AN ANALYSIS OF URBAN LANDSCAPES WITH RESPECT TO SOLID ANGLES BASED ON COMPUTATIONAL GEOMETRY ALGORITHMS

The solid angle, which is closely related to the sky amount and sky factor, has been commonly used to assess urban landscapes. In this paper, we propose a new algorithm to calculate the solid angles of urban landscapes based on computational geometry. This algorithm enables us to incorporate the complicated landscapes which consist of multiple nonconvex polygons. Furthermore, using the algorithms, we assess the public space near Shibuya Station in terms of solid angles. In the analysis, we describe how advertising billboards disturb our visibility. We also develop the algorithm to calculate the sky amount and the sky factor, and evaluate both indexes.