Toshikazu Nishimura

Traffic prediction for mobile network using Holt-Winter’s exponential smoothing

This paper presents a technique for evaluation of future radio traffic of circuit switched services in Erlang for near-term outlook using Holt-Winters exponential smoothing. The proposed traffic prediction technique relies on analysis of traffic data on cells. We propose how to classify traffic data for prediction. The result from a trial in history data of commercial GSM/GPRS network is presented. It shows that predicted traffic is good fitted with original one within our classification. The technique should be used in automated overload warning and express estimation of future traffic for capacity planning.

Implementation of asynchronous predictive fetch to improve the performance of Ajax-enabled web applications

An implementation study of Asynchronous Predictive Fetch method to improve the performance of Ajax-enabled Web applications is presented. To evaluate the performance of the approach, two versions of Ajax-enabled Web applications that implemented the same user interface were developed. A number of trials were accomplished to collect performance data on each application when doing the same tasks. We found that the method provided a performance improvement of the average response time of 64.5%.

A distributed authentication mechanism for sharing an overlay network among multiple organizations

In this paper, we propose a distributed authentication mechanism for sharing an overlay network among multiple organizations in order to establish secure connections among members for each organization. By combining a layer 2 virtual private network technology with a method for transmitting authenticated frames like Point-to-point protocol over Ethernet, we can avoid the threat of spoofing attack or phishing on network layer. We have implemented the prototypes both for the Internet Applications over IP and for the voice switching networks that support organization / communities.

Geographical information retrieval system using semantic relationships between multiple layers

Current geographical information retrieval systems provide users with keyword-based searching capabilities. Users select a layer, input keywords which they want to search, then the retrieval system returns the matching features to users through a map interface. In such a system, each layer only serves as an independent representation for a group of geographical features, manages them physically, and no semantics are counted. Therefore, the problems of semantic heterogeneity caused by localized language and the ambiguity of natural language make that approach insufficient to satisfy the high quality retrieval requirement. In this research, we propose a method to add semantic capabilities to these systems by defining the semantic relationships between multiple layers on the map. Ontologies are utilized for describing the terms in the domain; each layer is set to belong to one or more terms in the Ontology, and their semantic relationships such as synonyms, hypernyms, hyponyms, and sibling are defined through the relationships between the terms. The architecture for Ontology-based Geographical Information Retrieval System (OGIRS) is provided, then an Ontology-based City Map Guide (OntoCMG) prototype system based on our architecture is introduced. The experimental result shows the system supporting semantic geographical information retrieval, it can retrieval the maps that match the retrieval terms on semantic, and improve the retrieval quality.

Automated troubleshooting of mobile networks based on alarm and performance data using bayesian networks

In this paper, we present an automated troubleshooting method for mobile networks based on alarm and performance data using two Bayesian Networks. The method provides online, reactive diagnosis of malfunction alarms using the Bayesian Network with alarm correlation and diagnosis of cells bad performance using another Bayesian network. The proposed method and models were used in a trial with history data of commercial GSM/GPRS network. The results of the trial show that diagnosis accuracy of proposed method is better by about 10% than in current researches, especially in identification of base stations hardware faults -better by about 20%.

Fairy in a Smart IC Card: Interfacing People, Town, and Digital City

The performance of recent smart IC cards is equal to the one of microcomputers about twenty years ago. Using the functions of smart IC cards, this paper proposes Fairy-Wing: yet another mobile computing system for community computing in a digital city. The system aims at supporting personal information management, information services, and dynamic collaborative filtering in order to interface the people, towns, and digital cities. The main features of the system are that (1) the agents or fairies are small, cheap, and easyto-use; (2) they are fully distributed among ubiquitous computing environments with and/or without computer networks; and (3) holder-centered information controlling mechanisms. The application candidates in digital cities include travel navigation, collaborative education, and electronic commerce. This paper discusses the system architecture, feasibility of applications, Group Trip Advisor: a prototype of Fairy-Wing, and future issues.

Integrated Wireless Authentication System: Sharing Satellite Communication among Multiple Organizations after Natural Disasters

The catastrophic earthquake and Tsunami of Tohoku Japan in 2011, caused colossal damages to the ground infrastructures that resulted in the lost of means to acquire and to convey information between rescues and victims of disaster. This unfortunate situation of helplessness prompted us to propose in this paper a reliable means to recover a function of telecom infrastructure immediately by use of portable satellite phone with narrow band. The proposed system consists of sharing Internet access through satellite phone among multiple users and protocol conversion to improve the degraded performance caused by long-latency over satellite communication. The protocol conversion from application protocol like HTTP (Hypertext Transfer Protocol) over TCP (Transmission Control Protocol) to batch-oriented reliable protocol with forward error collection is presented. Through the implementation, we shows that the satellite communication is stabilized even in narrow band and it can be shared among many disaster victims.

Virtual-single-cell wireless networks with 3G-LTE-based protocol and PON for backhaul network

This paper presents possibility of dense small cell network for local areas from a view of network control considering two types of applications; one is 100m cells for a major road supporting vehicles mobility and another one is 10m cells for campuses supporting walking mobility. They adopt 3GLTE protocol after slight modification. Handover is directly triggered from a UE (User Equipment) to a target BS (base station) to shorten the handover period though it is relayed on a serving BS in conventional systems while drawing large latency due to backhaul communications. The direct request uses SR (Schedule Request) signal on PUCCH (Physical Uplink Control Channel) of 3G-LTE protocol. This can be allowed by short propagating delay in a small cell and synchronous operation of all BSs under clock of PON (Passive Optical Network) used for the backhaul network. Handover resources like SR codes, downward frames, and terminal ID are reserved among the target UE and a group of BSs next to one serving the target UE before handover. Cells surrounding the target UE follow the move of the UE always confining the target UE in the cells with the reserved handover resources.

Hot spots evolution to a new wireless LAN with mobility support

This paper proposes a new type of cellular network allowing quick handover (HO) even though all are small cells. The objective of the network is packet transfer with little handover gap. All small cells in a localized area are connected with PON (Passive Optical Network) as the cost-effective backhaul network accommodating large number of BSs (Base Stations). Used protocol is based on 3G-LTE system easing procedures of handover and of roaming with widely-spread mobile network. The UE (User Equipment) directly requests HO to the target BS to reduce the HO gap, though the serving BS relays it in the conventional procedures. For this, neighboring BSs of the serving BS prepare handover resources like ID, downward packets in advance to HO, and the 3G-LTE protocol is slightly modified. One of the applications of the new network is a campus network replacing conventional LANs integrating telephone and IP access infrastructure.

A Flexible Router with Tangible Network Interfaces for Sharing a Last Mile

After the big earthquake in 2011 in Japan, the disaster survivors lost the means to acquire and convey information in the stricken area. In this paper, we propose a means to share seamless access to the Internet immediately among survivors using surviving access lines including ground infrastructures and satellite communications even if disaster exceeds assumption. We introduce the notion of TNI (Tangible Network Interface) that can easily configure small handy router named Flexible Router on site without configuring the settings of router from external console device. We also introduce Integrated Wireless Authentication System to share Internet access line among disaster survivors. We implemented Flexible Router and its TNIs and demonstrate its performance.