본 논문은 실시간 전송을 위한 신뢰적 실시간 데이터 전송 프로토콜을 제안한다. 재전송은 전송 장애를 복구하는 방법으로 알려져 있지만, 딜레이로 인해 실시간 전송 요구사항에 위배될 수 있다. 제안하는 프로토콜은 브로드캐스팅과 시간적 기회 배분 방법을 이용한다. 센서노드의 전송범위 내에는 실시간 전송 요구사항을 만족하는 다수의 이웃노드가 존재할 수 있다. 모든 이웃노드들은 한 센서노드로부터 브로드캐스팅된 데이터를 수신할 수 있고, 각 이웃노드는 시간적 기회 배분 방법을 이용하여 배정된 전송 시간슬롯에 다음 홉 노드에게 데이터를 전달한다. 시간적 기회 배분 방법은 데이터 전송이 가능한 시간슬롯과 실시간 전송 요구사항을 만족시키는 전송 허용시간을 이용한다. 송신노드는 전송 제한시간을 전송 허용시간으로 나누어 다수의 시간슬롯을 생성하며, 각 이웃노드의 전송 허용시간에 따라 하나의 시간슬롯에 다수의 센서노드가 포함 될 수 있다. 각 시간슬롯에서 전송 허용시간이 가장 짧은 노드부터 전송 우선권을 부여해 가능한 많은 노드에게 데이터 전달 기회를 제공한다.

あらまし モバイルアドホックネットワーク(MANET)の有望な利用方法の一つは車々間通信である.本論 文は車々間通信を対象としたアドホックネットワーク(VANET)に関する論文のサーベイである.主な内容は 次のとおりである.まず,車々間通信の特徴について述べ,VANET と一般的な MANETの特徴,相違点を示 す.次に,VANET の主なアプリケーションを運転支援サービス,道路交通情報サービス,ユーザ通信・情報 サービスの三つに分類して示す.近い将来大多数の車が GPS,ディジタル道路地図などを装備することを想定 し,位置情報を利用するルーチングプロトコルに注目する.具体的にはユニキャストとジオキャストに関して, それらを実現する多くのルーチングプロトコルの提案を二つの代表的なアプローチ,次ホップ中継方式と指向型 フラッディングに分類し,それぞれの特徴,課題をまとめる.最後に,VANETアプリケーションの代表例とし て,アラーム転送方式と道路交通情報サービスを示す. キーワード 車々間通信,VANET,アドホックネットワーク,ジオキャスト,フラッディング

− Mobile ad-hoc network which is infrastructure less in topology. That is MANET does not have any infrastructure based topology. Because the mobiles are in dynamic nature. So MANET are not depend upon the fixed topology. By the dynamic nature of mobile nodes we can’t find the exact location of node in the network. In existing system by using adaptive position upadate in MANET they find the position of mobile nodes in the network. But the problem it doesn’t find the exact position of the mobile node in network. To overcome this problem we going to implement protocol called GPRS (Greedy Perimeter Stateless Routing).By this we can find the exact location of the node. In this we going to implement TCP protocol for ensure end-to-end delivery.

− In geographic routing, for making effectual forwarding decision, nodes require retaining up-to-date position of their immediate neighbors. A common approach used by most geographic routing protocols to retain their neighbor position is periodic broadcasting of beacon packets. These beacon packets include the geographic location of the nodes. It can be found that periodic beaconing in geographic routing increases the routing overhead and also reduces the network throughput. Another problem found is that a large transmission range and too small transmission range also reduces the performance. So a novel approach is proposed to solve these problems, which includes the Optimum Transmission Range and Adaptive Position Update (APU). Optimum transmission range finds an optimum radio transmission range for every node in the network, by using the single transmission distance energy efficiency. APU includes two rules, first one reduces the beacon overhead due to periodic beaconing and the second one allows the nodes that are involved in data forwarding to improve their local topology. The theoretical examinations are validated by using NS2 simulations of a geographic routing protocol, OnDemand Geographic Routing Protocol (OGRP), shows that APU with optimum transmission range can considerably reduce the routing overhead and improves the network performance and packet delivery ratio. Keyword-Geographic Routing Protocols; Optimum Transmission Range; Location System; OGRP

“Spreadsheet simulation” refers to the use of a spreadsheet as a platform for representing simulation models and performing simulation experiments. This tutorial explains the reasons for using this platform for simulation, discusses why this is frequently an efficient way to build simulation models and execute them, describes how to setup a spreadsheet simulation, and finally examines some limitations on the use of spreadsheets for simulation.

—One of the major concerns in VANETs is to design a scalable and robust routing protocol, which usually depends on the ability of tracking the locations of vehicles in VANETs. The location information service in VANETs helps to find the destination vehicle effectively. However, vehicle mobility and lack of adequate location information management scheme for vehicles in large scale VANETs are the main challenges. In this paper we proposed a novel group-based location information service scheme that places Location Information Points on the roadside to provide up-to-date location information and resolve lookup query of vehicles in the network. Furthermore, our proposed scheme groups LIPs into hotspot or non-hotspot groups. Hotspot LIPs will construct a P2P overlay network which facilitates the resolution of the query message in VANETs. Comparing to previous schemes, our scheme can perform location update and reply to lookup query on each LIPs well with less communication overhead in large scale VANETs.

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wireless multi-hop networks (AHWMNs) are communication networks that consist of wireless nodes, placed together in an ad hoc manner, i.e. with minimal prior planning. All nodes in the network have routing capabilities and forward data packets for other nodes in multi-hop fashion. AHWMNs pose substantially different challenges to routing protocols than more traditional wired networks. AHWMN routing protocols are classified as topology-based, position- based. Topology-based routing protocols use the information about the links that exist in the network to perform packet forwarding. Position based routing is a routing principle that relies on geographic information. Position-based routing algorithms require information about the physical position of the participating node. Commonly, each node determines its own position through the use of Global Positioning System (GPS). Decisions made based on destination position and position of forwarding nodes neighbours. A location service is used by the sender of packet to determine the position of the destination and to include it in the packet destination address. The Greedy Perimeter Stateless Routing Protocol is a novel routing protocol for wireless datagram networks. Greedy perimeter stateless routing is based on greedy packet forwarding to forward packets to nodes that always progressively closer to the destination in each step using local information. Thus, each node forwards the message to the neighbours that are most suitable from a local point of view. Greedy forwarding can lead into a dead end, way there is no neighbour closer to the destination. The algorithm recovers by routing around the perimeter of the region by keeping state only about the local topology; GPSR scales better in per- router state than shortest path and ad hoc routing protocols as the number of network destination increases. Under mobility's frequent topology changes, GPSR can use local topology information to find correct new routes quickly. In this paper performance of GPSR with the Ad hoc On demand distance Vector (AODV) routing protocol and Dynamic Source Routing (DSR) protocol is compared.

to-Peer (P2P) applications have been extensively used for file sharing and accounts for more than 70% of the traffic in the internet. The inherent characteristics of P2P make it advantageous in content distribution when compared to client- server architecture. In a P2P network, there is no clear distinction between client and server nodes, as every peer is both a client and a server at the same time. Thus, the time required to distribute data is lesser when compared to the client-server method. Due to the distributed and scalability of P2P, structured P2P approaches have also been proposed for ad-hoc networks. The potential for distributed P2P networking applications using a structured lookup algorithm such as Chord is enormous. However, whilst it has been proven that a structured approach improves lookup performance in a high bandwidth wired network; overlay networks may create unnecessary overhead that could negatively impact performance given an unstable environment such as a Wireless Mesh Network (WMN). In this paper, it is proposed to study existing CHORD protocols on WMN when nodes are static and dynamic.

the presence of malicious nodes, one of the main challenges in MANETs is to design a novel, scalable and robust Geographic Multicast Protocol (RSGM) that can protect MANETs from various routing attacks. The vulnerabilities in the RSGM protocol were explored and various attacks like blackhole, wormhole and flooding attack are simulated. Several virtual architectures are used in the protocol without need of maintaining state information for more robust and scalable membership management and packet forwarding in the presence of high network dynamics due to unstable wireless channels and node movements. Specifically, scalable and efficient group membership management is performed through a virtual-zone-based structure, and the location service for group members is integrated with the membership management. Both the control messages and data packets are forwarded along efficient tree- like paths, but there is no need to explicitly create and actively maintain a tree structure. The stateless virtual tree-based structures significantly reduce the tree management overhead, support more efficient transmissions, and make the transmissions much more robust to dynamics. Geographic forwarding is used to achieve scalability and robustness. Differences mechanisms have been proposed using various techniques to countermeasure the routing attack against MANETs. However, these mechanisms are not suitable for MANETs resource constraints. In a mobile scenario, mesh based protocols outperformed tree-based protocols. The availability of alternate routes provided robustness and scalability. The different routing attacks, such as flooding, blackhole and wormhole are simulated using NS2.28 version and efficient proactive counter measure is provided using HMAC function which would lead to a drastic change is performance metric like packet delivery ratio, control overhead and end to end delay which is used to prove that the proposed solution was efficient and robust. Keywordsattack, Wormhole attack, Flooding attack, RSGM.

of thesis entitled A COMPONENT-BASED SOFTWARE SYSTEM WITH FUNCTIONALITY ADAPTATION FOR MOBILE COMPUTING

ion & Presentation Layer

hoc Networks is challenging since it must efficiently handle rapid topology changes and a fragmented network. This paper proposes a new intersection-based geographical routing protocol called GyTAR (improved Greedy Traffic Aware Routing protocol) and capable to find robust routes within city environments. GyTAR consists of two modules: (i) dynamic selection of the junctions through which a packet must pass to reach its destination, and (ii) an improved greedy strategy used to forward packets between two junctions. GyTAR assumes the existence of an accurate traffic-information system that it requires to select paths with high connectivity. To address this issue, we also propose a completely decentralized mechanism for the estimation of traffic density in city-roads called IFTIS for Infrastructure-Free Traffic Information System. The proposed routing protocol shows significant performance improvement in a comparative simulation study with other routing approaches.

his paper focuses on the problem of implementing a distributed hash table (DHT) in wireless ad hoc networks. Scarceness of resources and node mobility turn routing into a challenging problem and therefore, we claim that building DHT as an overlay network (like in wired environments) is not the best option. Hence, we present a proof-of-concept DHT, called cell hash routing (CHR), designed from scratch to cope with problems like limited available energy, communication range or node mobility. CHR overcomes these problems, by using position information to organize a DHT of clusters instead of individual nodes. By using position-based routing on top of these clusters, CHR is very efficient. Furthermore, its localized routing and its load sharing schemes, make CHR very scalable in respect to network size and density. For these reasons, we believe that CHR is a simple and yet powerful adaptation of the DHT concept for wireless ad hoc environments.

a b s t r a c t Although vehicular sensing where mobile users in vehicles continuously gather, process, and share location-sensitive and context-sensitive sensor data (e.g., street images, road condition, traffic flow) is emerging, little effort has been investigated in a model-based energy-efficient network paradigm of sensor information sharing in vehicular environments. Upon these optimization frameworks, a suite of optimization subproblems: a program partitioning and network resource allocation problem, we propose a distributed vehicular sensing platform, called VeSense where mobile users in vehicles publish/access sensor data via a cloud computing-based distributed P2P overlay network. The key objective is to satisfy the vehicular sensing application’s quality of service requirements by modeling each subsystem: mobile clients, wireless network medium, and distributed cloud services. By simulations based on experimental data, we present the proposed system can achieve up to 37 times more energy-efficient and 73 times faster compared to a standalone mobile application, in various vehicular sensing scenarios applying a realistic mobility model.

ZusammenfassungComputersysteme, wie wir sie heute kennen, passen sich typischerweise nicht an den Benutzer und dessen Situation an. Erste Beispiele von Systemen, die durch den Bezug zur Realwelt den Kontext des Benutzers einbeziehen, sind Navigationssysteme, die unter Berücksichtigung der Position eines Benutzers und der Verkehrslage Richtungsanweisungen geben können. Damit innovative kontextbezogene Anwendungen möglich werden, muss der Kontext, also der Zustand der Realwelt, durch Sensoren erfasst, in das Computersystem übermittelt und dort in Form dynamischer Umgebungsmodelle den Anwendungen zur Verfügung gestellt werden.Der von der Deutschen Forschungsgemeinschaft geförderte und im Januar 2003 an der Universität Stuttgart eingerichtete Sonderforschungsbereich SFB 627 ,,Umgebungsmodelle für mobile kontextbezogene Anwendungen“ [22] ist ein interdisziplinärer Forschungsverbund von über 30 Wissenschaftlern. Diese erforschen Methoden und Konzepte für die Definition, Erstellung und Verwaltung von Umgebungsmodellen, durch die Anwendungen Zugriff auf Kontextinformationen erhalten.

Yan Yan1,2, Baoxian Zhang2,3, Jun Zheng4∗,† and Jian Ma5 1Institute of Computing Technology, Chinese Academy of Sciences, Beijing 100080, China 2CCCE, Graduate University of Chinese Academy of Sciences, Beijing 100049, China 3Key Lab of Wireless Sensor Network and Communications, Shanghai Institute of Microsystem and Information Technology of Chinese Academy of Sciences, Shanghai 200050, China 4School of Information Science and Engineering, Southeast University, Nanjing, Jiangsu 210096, China 5Nokia Research Center, Beijing 100176, China

Within wireless sensor networks, the location of the sensor can be a critical attribute of the data sensed. A device knowing its relative position to the other devices in the wireless network or its absolute position with respect to a map increases the value of the data sensed. Sensing the precise location of wireless devices has been a topic of serious study for some time. A number of methods and techniques have been suggested, using various physical attributes (IR, acoustic, time of flight); however, we have chosen to emphasize received signal strength (RSS), which is simple to implement and uses the signal strength sampling capability used by the network layer of a wireless network. Using algorithms such as fingerprinting and multilateration, a reasonably accurate position estimate can be established depending on the density of the network devices and the environment in which they must operate. We discuss the previous work in RSS localization and describe the limitations of these algorithms from a practical and an experimental perspective. We will conclude with a discussion of our work using these algorithms in 3 wireless network test beds constructed in an industrial refinery and an office environment.

With today’s rapidly improving link-layer technology, and the widespread adoption of wireless networking, the creation of large-scale ad hoc networks could be construed as all but inevitable. However, for routing in a network to be feasible, there is a pressing need for a scalable ad hoc routing protocol. Applications for large-scale ad hoc networking include consumer owned networks, tactical military networks, natural disaster recovery services and vehicular networks.

With the technology advances in wireless network, a large number of mobile devices for communication are now publicly available. However, the traditional wireless networks are based on infrastructure modes with some administration in the system. Deployment of such networks takes time and cannot be set up in time of emergency. Therefore, mobile multi-hop radio networks, also called mobile ad hoc networks(MANETs), play a critical role in places where infrastructure is neither available nor economical to build. However MANETs are usually limited in terms of bandwidth, energy, processing capabilities, and security. These problems result in some interesting issues. Scalability issue is an attractive one among them. In this thesis, we focus on the scalability study on the routing in MANETS. We analyze the existing routing approaches in MANETs, we conclude that clustering and hierarchical routing are promising ways to improve the scalability of the routing based on the analysis. We propose an adaptive clustering scheme (RMACP: adaptive&cached cluster-based routing protocol) to reduce the maintenance overhead for clustering schemes. Simulation results show that without any routing performance degradation the RMACP can achieve much lower control overhead compared with other existing clustering techniques. In addition we describe a novel hierarchical approach for MANETs. We provide a thorough and detailed view of the hierarchical maintenance for hierarchical routing. Over the previous hierarchical routing approaches, our scheme has the following advantages. • Forwarding pointers are used in the maintenance of our hierarchical system to reduce maintenance overhead. • In our hierarchical system a random clustering based hierarchical routing algorithm(RCHR) is proposed to overcome the convergence problems found by traditional hierarchical approaches. i ATTENTION: The Singapore Copyright Act applies to the use of this document. Nanyang Technological University Library