Perspectives on IoT-oriented network simulation systems

The Internet of Things (IoT) paradigm is assumed to be a major component in the present and future Internet, with forecasts claiming a humongous number of devices connected in the near future, and applications fields spanning from agriculture, to healthcare. Despite this, the standardization efforts have not yet resulted in widely adopted standards, and the market is fragmented into multiple solutions both at physical andcommunication protocol levels. Moreover, IoT systems exacerbate the usual test bed limitations, e.g., scalability(very large number of devices), hardware compatibility, space, and price. Due to the above problems, simulation tools become an extremely interesting tool for studying IoT systems both for academia (newalgorithms), standardization (new protocols), and industry (what-if analysis). In this paper we will discuss what are the most relevant features and models that a simulation tool like ns-3 should prioritize to enable the above-mentioned needs from academia, standardization, and industry, and if they are achievable in the short,medium, or long term.


Spectrum Sharing between Cellular and Wi-Fi Networks based on Deep Reinforcement Learning

International journal of Computer Networks & Communications


Joint Channel Allocation and Routing for ZigBee/Wi-Fi Coexistent Networks

IEICE Transactions on Information and Systems


Interface Mode Assignment Method for SelfReconstruction of Wireless Mesh Networks Based on IEEE 802.11 InfrastructureMode

IEEJ Transactions on Electrical and Electronic Engineering


Joint Bandwidth Assignment and Routing for Power Saving on Large File Transfer with Time Constraints


A ZigBee/Wi-Fi Cooperative Channel Control Method and Its Prototyping


Empirical Discussion of Reliable Wireless Communications in Vehicles

Recent works on enhancing the comfort and convenience of vehicles have revealed the advantage of various wireless sensor nodes for information collection. For the highly required reliability in vehicles, Reliable Wireless Communication based on Substitute Forwarding (RWCSF) has been proposed. It ensures that 99.999% of communications can finish within 20ms, which is the quality of communication equivalent to wired links. However, the performance was evaluated in very limited situations, where two or more communications never occurred simultaneously and no noise was present. In this paper, we enhance RWCSF to achieve the target communication quality even if two or more communications occur simultaneously. In addition, we evaluate the enhanced method in various types of vehicles that create internal noise.


Public WLAN Virtualization for Multiple Services

The recent widespread use of high-performance terminals has resulted in a rapid increase in mobile data traffic. Therefore, public wireless local area networks (WLANs) are being used often to supplement the cellular networks. Capacity improvement through the dense deployment of access points (APs) is being considered. However, the effective throughput degrades significantly when many users connect to a single AP. In this paper, users are classified into guaranteed bit rate (GBR) users and best effort (BE) users, and we propose a network model to provide those services. In the proposed model, physical APs and the bandwidths are assigned to each service class dynamically using a virtual AP configuration and a virtualized backhaul network, for reducing the call-blocking probability of GBR users and improving the satisfaction degree of BE users. Finally, we evaluate the performance of the proposed model through simulation experiments and discuss its feasibility.


Joint Bandwidth Scheduling and Routing Method for Large File Transfer with Time Constraint and its Implementation

In recent years, the number of requests to transfer large files via large high-speed computer networks has been increasing rapidly. Typically, these requests are handled in the "best effort" manner which results in unpredictable completion times. In this paper, we consider a model where a transfer request either must be completed by a user-specified deadline or must be rejected if its deadline cannot be satisfied. We propose a bandwidth scheduling method and a routing method for reducing the call-blocking probability in a bandwidth-guaranteed network. Finally, we show their excellent performance by simulation experiments.


A Spectrum Sharing Method Based on Users Behavior and Providers Profit

In recent years, spectrum sharing has received much attention as a technique for more efficient spectrum use. In the case in which all providers are cooperative, spectrum sensing can easily be realized and can improve user throughput (on average). If that is not the case, providers are not cooperative, i.e., spectrum trading, spectrum bands are rented to promote spectrum sharing. To ensure more profit, however, non-cooperative providers must correctly estimate the fluctuation of the number of connected users to be able to determine the offered channel price. In this paper, we propose a spectrum sharing method to achieve both higher throughput and provider profit via appropriate pricing using a disaggregate behavioral model. Finally, we confirm the effectiveness of the proposed method using simulation experiments.


Fair Routing for Overlapped Cooperative Heterogeneous Wireless Sensor Networks


自動車内における高信頼通信の実証的検討

自動車内における高信頼通信の実証的検討

近年，自動車内における快適性と利便性の向上に，小型かつ配線が不要なため設置が容易な無線センサノードの活用が検討されている．このとき，コスト削減のためには広く普及した汎用デバイスを利用することが望ましいが，WiFiやZigBeeに代表される既存プロトコルでは，実用上十分な信頼性が得られない．そこで本論文では，既存のデバイスを用いて，所定の値以下の遅延で十分に高い成功率で完了する方法について実証的に検討する．具体的には，自動車内の電波伝搬特性を実験によって明らかにした上で，オーバーヒアしたフレームを中継することでロス率を下げる代理通信方式を提案する．そして，CSMA/CAのコンテンションウィンドウサイズ調整を行い，必要となる回線速度を明らかにする．最後に，実験データに基づく性能評価によって，自動車内でのセンサノード間通信が，10ms以内に99.9%以上の成功率で達成できることを確認した．

The Transactions of the Institute of Electronics, Information and Communication Engineers B

電子情報通信学会論文誌(B)


ネット ワーク制御を一元化したサービス提供プラットホームの提案と実装

ネット ワーク制御を一元化したサービス提供プラットホームの提案と実装

電子情報通信学会論文誌(B)


An Efficient Spectrum Sharing Method Based on Genetic Algorithm in Heterogeneous Wireless Network

International journal of Computer Networks & Communications


A Fair and Efficient Agent Scheduling Method for Content-based Information Retrieval with Individual Time Constraints and Its Implementation

The recent explosive growth in information networks has driven a huge increase in content. For efficient and flexible information retrieval over such large networks, agent technology has received much attention. We previously proposed an agent execution control method for time-constrained information retrieval that finds better results by terminating an agent that has already acquired results of high-enough quality or one that is unlikely to improve the quality of results with continued retrieval. However, this method assumed that all agents have identical time constraints. This leads to a disparity in the obtained score between users who give individual time constraints. In this paper, we propose a fair and efficient scheduling method based on the expected improvement of the highest score (EIS). The proposed method allocates all CPU resources to the agent that has the highest EIS to decrease the difference between users' scores and to increase the mean highest score of requested results.


Joint Spectrum Sharing and Routing for WiFi/WiMAX Interworking Mesh Networks

International Journal of Multimedia Technology


A Hybrid Routing Method for Wireless Sensor Networks with Heterogeneous Node Types

ノード性能の不均質な無線センサネットワークのためのハイブリッド型ルーチング方式

無線センサネットワークでは消費電力の効率化によるネットワーク寿命の延長が重要な課題であり,クラスタを作成し,多数のノードからのデータを集約することにより効率的な通信を可能とするクラスタリング型プロトコルがよく用いられるが,全てのデータはシンクに向けて伝送されるため,シンク近辺では負荷が集中するという問題がある.一方で,全ノードがシンクに向けたマルチホップ通信によってデータを転送する非クラスタリング型プロトコルでは,各ノードの役割に差が少ないため転送負荷の偏りが生じにくいが,集約可能なデータ量が少ないため,転送データ量の削減が難しい.また,最近では,少数の高性能ノードを導入することで,低コストで効率的にネットワークの寿命を延長する方式が注目されている.そこで本論文では,ノード性能の不均質な無線センサネットワークにおいて,クラスタリングによるデータ集約と,シンク周辺での非クラスタリング型マルチホップ通信による負荷分散とを併用したハイブリッド型ルーチング方式を提案する.提案方式では,シンクから遠距離のノードはクラスタリングを利用して効率的にシンク周辺までデータを転送し,シンク周辺では非クラスタリング型マルチホップ通信によって各ノードの負荷を分散させる.更に,利用されるノードの性能とセンシングの対象範囲から,クラスタリング型と非クラスタリング型の境界となる距離の最適値を数学解析モデルによって近似的に導出する.最後に,計算機シミュレーションによって提案方式の有効性を評価する.

電子情報通信学会論文誌(B)


A Unified Failure Detection Method for Network Services Based on Distributed Components

International Journal of Information Technology and Network Application (IJITNA)


A Dynamic Spectrum Assignment Method for Call Blocking Probability Reduction in WiFi/WiMAX Integrated Networks

With advances in communication technologies, network services provided via the Internet have become widely diversified, and people can use these services not only via wired networks but also via wireless networks. There are several wireless systems in practical use such as cellular, WiMAX and WiFi. Although these wireless network systems have developed independently of each other, they should be integrated for seamless access by users. However, each system uses an individual spectrum prescribed by law to avoid radio interference. To overcome such a situation, dynamic spectrum access technology is receiving much attention. We propose a dynamic spectrum assignment method in which a WiFi system temporarily uses a spectrum band of the WiMAX system in WiFi/WiMAX integrated networks to reduce call blocking probability of multimedia communication services. We confirm the effectiveness of the proposed method by simulation experiments.


A Clustering Method for Wireless Sensor Networks with Heterogeneous Node Types

Wireless Sensor Networks (WSNs) are gradually moving toward the adoption of clustered heterogeneous designs, incorporating a mixture of variety kinds of sensor nodes with different radio coverage and battery capacity. Compared with homogeneous networks, heterogeneous networks are able to reduce the initial cost of the network or prolong the network lifetime. The architecture and routing protocol for this type of heterogeneous WSN should be energy aware in order to prolong the lifetime of the network. However, most of the existing clustering methods consider only initial energy of the sensor nodes and ignore the non-uniform energy drainage caused by many-to-one traffic near sink and/or cluster heads in heterogeneous network environment. In this paper, we propose a new clustering method for WSN with heterogeneous node types which selects cluster heads considering not only the transmission power and residual energy of each node but also those of its adjacent nodes. Simulation experiments show that the proposed method increases network lifetime by 80% and 60% more than that of the CC and HEED, respectively.


An Efficient Agent Execution Control Method for Content-based Information Retrieval with Time Constraints

Networks have gotten bigger recently, and users have a more difficult time finding the information that they want. The use of mobile agents to help users effectively retrieve information has garnered a lot of attention. In this paper, we propose an agent control method for time constrained information retrieval. We pay attention to the highest past score gained by the agents and control the agents with the expectation of achieving better scores. Using computer simulations, we confirmed that our control method gave the best improvement over the whole network while reducing the overall variance. From these results, we can say that our control method improves the quality of information retrieved by the agent.


A Fault Tolerant Service Platform Providing Stable QoS Based on Distributed Component Management

分散コンポーネント管理により耐障害性と安定したQoSを実現するサービスプラットフォーム

遠隔ノード上に分散配置された複数種類のコンポーネントを利用してアプリケーションを提供するネットワークサービスへの注目が高まっている.このネットワークサービスにおいては,全てのコンポーネントを新たに用意する必要がないためサービスの設置コストが小さい,コンポーネント間の連携によってより高度なサービスを提供できるなどの利点がある.本論文では,このような分散コンポーネントを基盤としたネットワークサービスにおいて,コンポーネント間でオーバレイネットワークを構築し,自律的に情報を共有することで耐障害性をもち,ユーザからのサービス要求に対して安定したQoSを提供できるサービスプラットホームを提案する.

The Transactions of the Institute of Electronics, Information and Communication Engineers B

電子情報通信学会論文誌(B)


レイヤ2ネットワークにおけるループ障害のリモート診断方式

レイヤ2ネットワークにおけるループ障害のリモート診断方式

Transactions of Information Processing Society of Japan


ネットワーク・端末総合系におけるTCPスループット上限値の導出

ネットワーク・端末総合系におけるTCPスループット上限値の導出

電子情報通信学会論文誌(B)


A Design of Wide Area MANET by Dynamic Linkage with IP-Based Infrastructure

In this paper, we propose a new method using dynamic linkage with IP-based infrastructure to compose a wide-area MANET. The proposed method extends AODV and enables searches for destinations in the IP-based infrastructure. The proposed method settles the low scalability problem by creating shortcuts in the IP network. In addition, to overcome the geographical dependence problem, the proposed method connects terminals that are out of radio range with each other by using the IP-based infrastructure. In this way, the proposed method can flexibly establish a wide-area MANET that is scalable and free from geographical constraint.


An Efficient Agent Control Method for Time-Constrained Applications

As one of the technologies for the retrieval of desired contents over large-scale networks, multi-agent systems are receiving much attention. Since there are too many contents on the network to search them all exhaustively, some applications on multi-agent systems have time constraints, that is, they must obtain a result by a given deadline. To find better results for such applications, it is important for the agents to complete their tasks on as many nodes as possible by the deadline. However, most existing agent systems using round robin scheduling disciplines do not take time constraints into account. Therefore, agents are likely to miss their deadlines on many nodes. In this paper, we propose an efficient agent-dispatching method for time-constrained applications. This method decides creation and migration of a clone agent according to the estimated value of the number of agents that would have completed their tasks by the deadline. The results of our performance evaluation show that the proposed method increases the number of agents that complete their tasks.


A Distributed Network Mobility Management Scheme for Hierarchical Mobile IPv6 Networks

Route optimization for network mobility is a key technique for providing a node in a mobile network (Mobile Network Node or MNN) with high quality broadband communications. Many schemes adding route optimization function to Network Mobility (NEMO) Basic Support protocol, the standardized network mobility management protocol from the IETF nemo working group, have already been proposed in recent years. One such scheme, a scheme using Hierarchical Mobile IPv6 (HMIPv6) aims to overcome micromobility management issues as well by applying a mechanism based on HMIPv6. The traditional scheme, however, suffers from a significant number of signaling messages as the number of MNNs and/or the number of their Correspondent Nodes (CNs) increase, because many messages notifying the MNNs' Home Agents (HAMNNs) and the CNs of the mobile network's movement are generated simultaneously each time the mobile network moves to the domain of another micromobility management router (Mobility Anchor Point or MAP). This paper proposes a scheme to overcome this problem. Our scheme reduces the number of signaling messages generated at the same time by managing the mobility of MNNs using multiple MAPs distributed within a network for load sharing. The results of simulation experiments show that our scheme works efficiently compared to the traditional scheme when a mobile network has many MNNs and/or these MNNs communicate with many CNs.


情報の連想的結合によるコンテキストアウェアサービス制御方式

情報の連想的結合によるコンテキストアウェアサービス制御方式

電子情報通信学会論文誌(B)


A Fair and Effective Scheduling Algorithm for Multi-Agent Systems

マルチエージェントシステムのための公平かつ効率的なスケジューリングアルゴリズム

マルチエージェントシステムでは,クローンエージェントを並列に動作させることで,ネットワーク上の複数のノードでの処理を効率良く実行することができる.そのようなシステムにおいて,ユーザが指定したすべてのノードにクローンエージェントを動作させ,所望の処理を行わせるようなアプリケーションでは,最後のクローンエージェントが処理を完了するまでの時間を短くすることが重要である.しかし,このようなアプリーションにはクラスタコンピューティングやグリッドシステムのような分散システムスケジューリングをそのまま適用することはできないため,一般のOSのスケジューリングを利用することが多い.そこで本論文では,処理中のエージェント数・各ノードの処理能力・エージェントのワークデマンドを考慮した上で,ネットワーク全体で処理中のクローンエージェント数の少ないエージェントに優先的にCPUを割り当てることで,平均応答時間を短縮し,同時に,同一のユーザに生成されたエージェント群に対して与えられるCPU資源の総量を一定にすることで,応答時間の分散を小さくし,公平性を保つアルゴリズムを提案する.最後に計算機シミュレーションによる性能評価を行い,提案方式の有効性を示す.

電子情報通信学会論文誌(B)


Multilevel Hierarchical Mobility Management in Densely Meshed Networks

Micromobility management is a key issue for the deployment of broadband mobile communication services. The packet loss during handover and the handover latency need to be minimized to maintain the high quality of these services. We have previously proposed a mobility management scheme that addresses this issue in wide-area mobile networks that employed hierarchical multiple mobility management routers (Mobility Anchor Points or MAPs). Our scheme directs a Mobile Terminal (MT) to a suitable MAP to fully minimize packet loss during handover, and handover latency of the MTs. In our previous work, we confirmed the effectiveness of our scheme using a simple tree network. Actual networks however, always have densely meshed topologies to provide some redundancy for the elimination of single points of failure. In such networks, it is difficult to deduce the relationships between the MAPs, and this makes it difficult for our scheme to select a suitable MAP for an MT, because the selection is performed using both the MT's smoothed speed and the relationships existing between the MAPs located above the Access Router (AR), to which the MT is connected. In this paper, we propose a method to overcome this problem, by autonomously adjusting the selection criteria that are individually configured for use at a particular AR, and we evaluate this method using simulation experiments. The results show that our mobility management scheme works well in densely meshed networks using the proposed additional method.


Enhanced Flooding Algorithms Introducing the Concept of Biotic Growth


Enhanced Fallback+: An Efficient Multiconstraint Path Selection Algorithm for QoS Routing

In future high-speed networks, provision of diverse multimedia services with strict quality-of-service (QoS) requirements, such as bandwidth, delay and so on, is desired. QoS routing is a possible solution to handle these services. Generally, a path selection for QoS routing is formulated as a shortest path problem subject to multiple constraints. However, it is known to be NP-complete when more than one QoS constraint is imposed. As a result, many heuristic algorithms have been proposed so far. The authors proposed a path selection algorithm Fallback+ for QoS routing, which focuses not only on the path selection with multiple constraints but also on the efficient use of network resources. This paper proposes an enhanced version of Fallbacks, named Enhanced Fallback+, where in a shrewd way, it keeps tentative paths produced in the conventional Fallback algorithm with Dijkstra's algorithm. Simulation experiments prove the excellent performance of Enhanced Fallbacks, compared with the original Fallback+ and other existing path selection algorithms.


A Study on Estimation of Mobility of Terminals for Hierarchical Mobility Management Scheme

Hierarchical Mobile IPv6 (HMIPv6) has been proposed to manage the mobility of Mobile Terminals (MTs) hierarchically to reduce packet losses during local handover. HMIPv6 uses a mobility manageable router in a domain visited by the MTs to manage the micromobility of the MTs. The router is called Mobility Anchor Point (MAP). As a hierarchical mobility management scheme based on HMIPv6, we have already proposed a multilevel hierarchical distributed IP mobility management scheme to manage the mobility of MTs in a decentralized manner using multiple MAPs. Our scheme manages the mobility of an MT using a MAP having a suitable management domain. This usage of MAPs aims to efficiently decentralize the load of mobility management. Our scheme estimates the movement speed of the MT and then estimates the mobility of the MT based on the estimated movement speed of the MT to achieve the objective. However, recent simulation results obtained with more realistic mobility model indicate that our scheme has two problems in estimating the mobility of MTs: One is that our current scheme misestimates the movement speed of an MT in some cases, and the other is that our current scheme does not notice the changes in the mobility of an MT when the MT decelerates and stays in the same access area for a long time. Thus, an enhanced mobility estimation method is proposed in this paper. The enhanced method has an ability to estimate the movement speed of MTs more correctly and an ability to urge decelerated MTs to degrade their MAP quickly. Finally, the performance of the proposed mobility estimation method is evaluated using simulation experiments. The simulation results show that the enhanced method allows our scheme to estimate the mobility of MTs more correctly and so achieve more efficient load sharing.


A Design for Integrated Wireless Network with Flexible Bandwidth Assignment

As various mobile communication systems have developed, dramatically integrated wireless network, where users can communicate seamlessly via several wireless access systems, have become expected. At present, there are many studies of integrated wireless network, but no study of a network design method. Therefore, in this paper, we discuss a network design method for integrated wireless networks. Because of the handover procedure, the network design where adjacent base stations are connected to the same router, regardless of radio system type, is simply considered. However, in such a design, where mobile users crowd into a particular area and users' access to the base stations located there increases, the load of these accesses is centralized to the single router. To overcome this problem, we propose a new network design wherein the base stations of heterogeneous wireless communication systems, the service areas of which overlap, are connected to a different router. In the proposed network design, although users' accesses are concentrated on the base stations located in a particular area, users in that area can be assigned bandwidth of several upper links according to the access conditions of the base stations in neighboring areas. Finally, we show the excellent performance of the proposed design by simulation experiments.


A Multipoint-to-Multipoint Routing Method for Load Balanced Communications in Large Scale Networks


A Location Transparent Multi-Agent System with Terminal Mobility Support

Lecture Notes in Computer Science (LNCS)


複数のQoS要求を満たすマルチキャストツリーを生成するリンク状態アルゴリズム

複数のQoS要求を満たすマルチキャストツリーを生成するリンク状態アルゴリズム

The Transactions of the Institute of Electronics, Information and Communication Engineers B

電子情報通信学会論文誌(B)


A Mobility-Based Terminal Management in Ipv6 Networks


Network Map Architecture using Inter-Agent Communication Techniques for Multiple QoS Routing


複数のQoSを考慮したサービス情報検索方式

複数のQoSを考慮したサービス情報検索方式

電子情報通信学会論文誌(B)


複数のQoS要求を満たす経路選択アルゴリズム Fallback+ の提案

複数のQoS要求を満たす経路選択アルゴリズム Fallback+ の提案

電子情報通信学会論文誌(B)


多対多地点間通信のための経路制御とネットワーク構成法

多対多地点間通信のための経路制御とネットワーク構成法

電子情報通信学会論文誌(B)


Holonic Network: A New Network Architecture for Personalized Multimedia Communications Based on Autonomous Routing


Technologies and Emergency Management for Disaster Recovery - With Focus on the Great East Japan Earthquake