International Journal of Space-Based and Situated Computing (7 papers in press)
A Throughput Estimation Model under Two-Link Concurrent Communications with Partially Overlapping Channels and Its Application to Channel Assignment in IEEE 802.11n WLAN
by Ismael Munene Kwenga, Nobuo Funabiki, Minoru Kuribayashi, Rahardhita Widyatra Sudibyo, Wen-Chung Kao
Abstract: Currently, the IEEE 802.11n wireless local-area network (WLAN) has been deployed world-wide due to exibility and low costs. A key challenge in the WLAN deployment is to provide high data-rate under strong interferences due to the limited frequency channels. In WLAN, the adjacent channels are partially overlapped with each other, called partially overlapping channels (POCs). Then, the optimal POC assignment to the access-points (APs) in WLAN using the mathematical model is important to improve the performance, particularly for usage of the channel bonding. In this paper, we propose the throughput estimation model extension for concurrent communications of two IEEE 802.11n links under interferences using POCs and the channel bonding, from extensive measurement results under a variety of conditions. Then, based on this model, we present the channel assignment extension in the active AP configuration algorithm for the elastic WLAN system, which dynamically optimizes the topology depending on network conditions. For the evaluation, we verify the model accuracy through comparing estimated throughputs with measured ones under various conditions. On top of that, we confirm throughput improvements by adopting POCs from using merely orthogonal
channels (OCs) in simulations and experiments in several topologies.
Keywords: WLAN; access point; IEEE 802.11n; partially overlapping channel; throughput estimation model; channel assignment.
A Dynamic Model for Energy-efficiently Migrating a Group of Virtual Machines from a Host Server to a Guest Server
by Dilawaer Duolikun, Tomoya Enokido, Makoto Takizawa
Abstract: In this paper, we newly propose a DMG(v) (Dynamic Migration of a Group ofrnv virtual machines) algorithm to reduce the total electric energy consumption of servers in a cluster. Here, virtual machines are dynamically resumed and suspended so that the number of processes on each virtual machine can be kept fewer. In addition, a group of v virtual machines migrates from a host server to a guest server so that the total electric energy consumed by the servers can be reduced. In our previous studies, time to migrate each virtual machine is assumed to be zero. In reality, there is migration time every process is suspended on a virtual machine migrating even in the live manner. Hence, the more often a virtual machine migrates, the longer time it takes to perform processes on the virtual machine. We propose a model to estimate electric energy to be consumed by servers through considering the migration time of each virtual machine. By using the estimation model, we can decide on which virtual machines on a host server to which guest server so that the total electric energy consumption of the host and guest servers can be reduced. In the evaluation, we show the total electric energy consumption of servers can be reduced by the DMG(v) algorithm compared with other algorithms.
Keywords: Energy-efficient computation; Power consumption model; Dynamic virtual machine migration; Group migration of virtual machines; DMG(v) algorithm.
An Implementation and Evaluation of IoT Application Development Method Based on Real Object Oriented Model
by Hiroyuki Suzuki, Akio Koyama
Abstract: Currently, various IoT applications are developing and used various fields such as industry, agriculture, health care, smart house and so on. Generally, the development model of IoT applications is still a vertical type model optimized for specific system. However, in vertical type model, when novel systems are developed, same functions of past developed system cannot use. As the results, the application development period becomes long. In this paper, we propose a novel IoT application development method based on Real Object Oriented Model which is a horizontal type development model. The proposed method can be applied in the application development without being conscious the middleware. In order to improve the development efficiency and reduce the development period, the proposed method automatically combines an application, and a middleware which is common platform of the development system, and transmit the combined code to devices, and automatically execute the code at the devices. In the evaluation, we evaluated amounts of source codes and development time for each method, and showed the usefulness of the proposed method compared with two conventional methods.
Keywords: Internet of Things (IoT); Real Object Oriented Model; Application development method; Vertical type model; Horizontal type model.
Distance Measurement Correction based on Feedback Filter for RSSI Localization Technique in WSNs
by Dhouha El Houssaini, Kamel Besbes, Olfa Kanoun
Abstract: Localization methods based on the Received Signal Strength Indicator (RSSI) are widely used in Wireless Sensor Networks (WSNs). They offer an energy reduced and cost-effective solutions for wireless localization. Due to radio irregularity, RSSI localization is vulnerable to multipath, shadowing, interference and environmental effects, which reduces the accuracy of localization results. In this paper, a new distance measurement correction algorithm is presented, which is based on feedback filter and hardware characteristic. It implements the feedback filter with consideration of historical values of RSSI. This enables to predict possible values of RSSI and thus nodes positions. Hardware characteristics, such as multiplication and summation capabilities are explored to improve the localization accuracy. Real experiments were carried out on panStamp sensor nodes at two different temperatures. The new proposed RSSI technique shows a reduced localization error compared to the simple RSSI method.
Keywords: WSNs; Localization; Distance correction; RSSI; Feedback filters; Computational capabilities, Temperature variation.
Special Issue on: Advanced Technologies for Next-Generation Communications and Networked Applications
Introduction to content centric network architectures replacing traditional location centric network
by Tetsuya Shigeyasu
Abstract: Nowadays, Internet has became most important infrastructure used by the population over the 38.8 billion.rnThe Internet is the inseparable from our daily life. The Internet based on such location centric communication, however, may induces high risk of networkrncongestion and network service down due to network traffic dominated by contents delivery and multimedia applications. rnThen, the concept of CCN (Content Centric Network) or ICN (Information Centric Network) has been attracting the attention to resolve the problems under the location based network architecture.rnThis paper explains the overview of the overview of network architectures based on CCN concept in order to help researchers developing well suited next-generation CCN based network architectures.
Keywords: content centric network; host centric network; in-network caching; caching algorithm.
Design and Evaluation of a Utility Tool for Recorded Class B AIS Data in an Unstable Maritime Environment
by Misako Urakami, Hisaya Motogi, Tomohiro Sunada, Kenshiro Okamura, Takayuki Watanabe, Nobukazu Wakabayashi
Abstract: We focus on the automatic identification system (AIS), which is a probe data system. Some researchers propose using this system not only to support ship handling, such as through collision avoidance, but also in other ways, such as for navigation time analysis, accident tracing, or navigation management by administrators on land. Therefore, we focus on the importance of obtaining more marine ship position information, including that for a small ship using Class B AIS, to enrich the intelligent transport system service for marine traffic. First, we develop a processing tool to create an operation management book from the recorded AIS data. We then study the implementation of these utility tools and evaluate their effectiveness.
Keywords: Information processing tool; Utility tool; Intelligent transport system; ITS for the sea; Probe data; Automatic identification system; Class A AIS; Class B AIS; Maritime environment; Navigation management; GPS;.
Ray-Tracing Analysis of the Radio Propagation on the Line-Of-Sight Maritime Wireless Environments
by Masaaki Yamanaka, Daiki Hashimoto, Yasuhiro Sato, Kohei Shimada, Yoshinori Matsuura
Abstract: Due to heavy maritime traffic, wireless systems play an important role to maintain the traffic safety. In this paper, we try to analyze the radio propagation of wireless systems in maritime environments. As the maritime radio wave propagation has not been amply analyzed yet, the method and the result presented in the paper will be a good guide to implement a system fit in the assumed location. Although, there are many wireless systems should be covered, we picked up a radar system in this paper. As the system uses direct wave to detect floating objects on sea surface, the main objective of this paper is to analyze the Line-Of-Sight maritime radio wave propagation. In general, radar antennas are set in the highest location from sea level in order to get a line-of-sight view for a wide area. However, there are cases when high islands or hills hamper the line-of-sight. In this case, the system is not able to see the area through the radio waves, which will cause a serious problems for navigation safety. We will try to assess the area using a ray-tracing method applied in the environment. The procedure of using the Geospatial Information Authority of Japan (GSI)'s topographical data is given, to assess the exact area where the radio waves are unable to reach, through simulation.
Keywords: Maritime traffic safety; Radio wave propagation analysis; Radar system; Ray-tracing method.