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Showing papers in "IEEE Communications Surveys and Tutorials in 2006"


Journal ArticleDOI
TL;DR: This article presents a survey of data-aggregation algorithms in wireless sensor networks and compares and contrast different algorithms on the basis of performance measures such as lifetime, latency, and data accuracy.
Abstract: Wireless sensor networks consist of sensor nodes with sensing and com- munication capabilities. We focus on data-aggregation problems in energy- constrained sensor networks. The main goal of data-aggregation algorithms is to gather and aggregate data in an energy efficient manner so that net- work lifetime is enhanced. In this article we present a survey of data-aggre- gation algorithms in wireless sensor networks. We compare and contrast different algorithms on the basis of performance measures such as lifetime, latency, and data accuracy. We conclude with possible future research directions.

943 citations


Journal ArticleDOI
TL;DR: This article outlines the constraints, security requirements, and attacks with their corresponding countermeasures in WSNs, and presents a holistic view of security issues, classified into five categories: cryptography, key management, secure routing, secure data aggregation, and intrusion detection.
Abstract: Wireless Sensor Networks (WSNs) are used in many applications in military, ecological, and health-related areas These applications often include the monitoring of sensitive information such as enemy movement on the battlefield or the location of personnel in a building Security is therefore important in WSNs However, WSNs suffer from many constraints, including low computation capability, small memory, limited energy resources, susceptibility to physical capture, and the use of insecure wireless communication channels These constraints make security in WSNs a challenge In this article we present a survey of security issues in WSNs First we outline the constraints, security requirements, and attacks with their corresponding countermeasures in WSNs We then present a holistic view of security issues These issues are classified into five categories: cryptography, key management, secure routing, secure data aggregation, and intrusion detection Along the way we highlight the advantages and disadvantages of various WSN security protocols and further compare and evaluate these protocols based on each of these five categories We also point out the open research issues in each subarea and conclude with possible future research directions on security in WSNs

929 citations


Journal ArticleDOI
TL;DR: This article captures the state of the art in routing protocols in DTNs with three main approaches: the tree approach, the space and time approach, and the modified shortest shortest path approach.
Abstract: n the last few years, there has been much research activity in mobile, wireless, ad hoc networks (MANET). MANETs are infrastructure-less, and nodes in the networks are constantly moving. In MANETs, nodes can directly communicate with each other if they enter each others' communication range. A node can terminate packets or forward packets (serve as a relay). Thus, a packet traverses an ad hoc network by being relayed from one node to another, until it reaches its destination. As nodes are moving, this becomes a challenging task, since the topology of the network is in constant change. How to find a destination, how to route to that destination, and how to insure robust communication in the face of constant topology change are major challenges in mobile ad hoc networks. Routing in mobile ad hoc networks is a well-studied topic. To accommodate the dynamic topology of mobile ad hoc networks, an abundance of routing protocols have recent-For all these routing protocols, it is implicitly assumed that the network is connected and there is a contemporaneous end-to-end path between any source and destination pair. However, in a physical ad hoc network, the assumption that there is a contemporaneous end-to-end path between any source and destination pair may not be true, as illustrated below. In MANETs, when nodes are in motion, links can be obstructed by intervening objects. When nodes must conserve power, links are shut down periodically. These events result in intermittent connectivity. At any given time, when no path exists between source and destination, network partition is said to occur. Thus, it is perfectly possible that two nodes may never be part of the same connected portion of the network. Figure 1 illustrates the time evolving behavior in intermittent-ABSTRACT Recently there has been much research activity in the emerging area of intermittently connected ad hoc networks and delay/disruption tolerant networks (DTN). There are different types of DTNs, depending on the nature of the network environment. Routing in DTNs is one of the key components in the DTN architecture. Therefore, in the last few years researchers have proposed different routing protocols for different types of DTNs. In this article we capture the state of the art in routing protocols in DTNs. We categorize these routing protocols based on information used. For deter-ministic time evolving networks, three main approaches are discussed: the tree approach, the space and time approach, and the modified shortest …

861 citations


Journal ArticleDOI
TL;DR: This article identifies and describes security problems in the SIP protocol that may lead to denial of service, including flooding attacks, security vulnerabilities in parser implementations, and attacks exploiting vulnerabilities at the signaling-application level.
Abstract: The open architecture of the Internet and the use of open standards like Session Initiation Protocol (SIP) constitute the provisioning of services (e.g., Internet telephony, instant messaging, presence, etc.) vulnerable to known Internet attacks, while at the same time introducing new security problems based on these standards that cannot been tackled with current security mechanisms. This article identifies and describes security problems in the SIP protocol that may lead to denial of service. Such security problems include flooding attacks, security vulnerabilities in parser implementations, and attacks exploiting vulnerabilities at the signaling-application level. A qualitative analysis of these security flaws and their impacts on SIP systems is presented.

198 citations


Journal ArticleDOI
TL;DR: The state of the art within key management for ad hoc networks is surveyed, and their applicability for network-layer security is analyzed, as this work was initiated by a study of security in MANETs for emergency and rescue operations.
Abstract: The wireless and dynamic nature of mobile ad hoc networks (MANETs) leaves them more vulnerable to security attacks than their wired counterparts. The nodes act both as routers and as communication end points. This makes the network layer more prone to security attacks. A main challenge is to judge whether or not a routing message originates from a trustworthy node. The solution thus far is cryptographically signed messages. The general assumption is that nodes in possession of a valid secret key can be trusted. Consequently, a secure and efficient key-management scheme is crucial. Keys are also required for protection of application data. However, the focus here is on network-layer management information. Whereas keymanagement schemes for the upper layers can assume an already running network service, schemes for the protection of the network layer cannot. Keys are a prerequisite to bootstrap a protected network service. This article surveys the state of the art within key management for ad hoc networks, and analyzes their applicability for network-layer security. The analysis puts some emphasis on their applicability in scenarios such as emergency and rescue operations, as this work was initiated by a study of security in MANETs for emergency and rescue operations.

162 citations


Journal ArticleDOI
TL;DR: The TCP/IP protocol stack is reviewed and there is no single solution perfectly addresses mobility support for the Internet, so a recommendation of features that need to be satisfied in Internet mobility support is concluded.
Abstract: With the development of mobile communication and Internet technology, there is a strong need to provide connectivity for roaming devices to communicate to other communication end point in the Internet at any time and anywhere. The key issue of this vision is how to support mobility in TCP/IP networks. In this paper, we review the TCP/IP protocol stack and analyze the problems associated with it in a mobile environment. We then investigate the mobility support techniques and existing solutions to provide mobility support in the Internet. We classify the proposed solutions based on the protocol layers and present examples for each category. We also provide a comparison of the different solutions belonging to different categories and in the same category, including their advantages and disadvantages, and conclude that there is no single solution perfectly addresses mobility support for the Internet. We conclude this survey with a recommendation of features that need to be satisfied in Internet mobility support.

154 citations


Journal ArticleDOI
TL;DR: An up-to-date, comprehensive literature survey on proposed handover schemes for LEO satellite systems, and a detailed classification of hand over schemes based on a common framework are presented.
Abstract: Low Earth Orbit (LEO) satellites will work as an important component in future data communication networks. LEO satellites provide low end-toend delays and efficient frequency spectrum utilization, making them suitable for personal communication. However, due to high satellite speed, ongoing communication using LEO constellations experiences frequent handover. In this article we provide an up-to-date, comprehensive literature survey on proposed handover schemes for LEO satellite systems. We also present a detailed classification of handover schemes based on a common framework. We first classify the schemes into link-layer and network-layer handover schemes. Link-layer handover schemes are further classified into three categories: spotbeam handover schemes, satellite handover schemes, and ISL handover schemes. Spotbeam handover schemes are categorized based on channel capacity, handover guarantee, and handover prioritization techniques. Network-layer handover schemes are also classified depending on connection transfer strategies. Finally, we compare the handover schemes using different quality of service (QoS) criteria.

111 citations


Journal ArticleDOI
TL;DR: The taxonomy and characteristics of wireless networks, and problems for TCP in wireless communications are introduced, and various representative algorithms which preserve the end-to-end semantics are examined.
Abstract: The Transmission Control Protocol (TCP) is the most popular transport layer protocol for the Internet. Due to the characteristics specific to wireless networks, such as signal fading and mobility, packets may be lost due to con- gestive and noncongestive losses. Substantial noncongestive losses violate the design principles of some traffic control mechanisms in TCP and thus pose performance problems. In this article we provide a comprehensive and in-depth survey on recent research in TCP for wireless communications. The taxonomy and characteristics of wireless networks, and problems for TCP in wireless communications are introduced. Various representative algorithms which preserve the end-to-end semantics are examined. Some open ques- tions are discussed in order to stimulate further research in this area.

100 citations


Journal ArticleDOI
TL;DR: A comprehensive survey of MPR-based broadcast schemes is presented, classified into three categories based on their objectives, and the evaluation of their performances is provided in light of their costs.
Abstract: Almost every routing protocol in mobile ad hoc networks (MANETs) depends on a broadcast scheme to disseminate routing information. For this reason, creating an efficient broadcast scheme is important and a large variety of approaches have been proposed. Among them, multipoint relay (MPR) is one of the distributed broadcast schemes which is efficient and simple. Based on the MPR concept, many broadcast schemes have been proposed, which generally focus on different performance issues. In this article we present a comprehensive survey of MPR-based broadcast schemes, classified into three categories based on their objectives. Different heuristics are described, and the evaluation of their performances is provided in light of their costs. Advantages and limitations of different broadcast schemes are also highlighted.

82 citations


Journal ArticleDOI
TL;DR: The objective is to review the performance issues of TCP variations, when employed in last-hop wireless networks, and to provide a categorized analysis of different existing solutions comparatively, as it is difficult to create a “one size fits all” TCP for last-hops wireless networks.
Abstract: TCP continues to be an important transport-layer communication protocol that is typically tuned to perform well in traditional wired networks, where bit error rate (BER) is low and congestion is the primary cause of packet loss. The emergence of various mobile access networks has prompted researchers to look for suitable modifications to TCP so as to make it survive in the wireless era as well. Networks with wireless links and mobile hosts incur significant losses due to high BER, host motion, and handoff mechanisms. Mobile devices face temporary and unannounced loss of network connectivity when they move. They are likely to have scarce resources, and they react to frequent changes in the environment. Motion causes varying, increased delays and packet losses, while the network learns how to deliver packets to the new location of the host. TCP incorrectly interprets these delays and losses as signs of network congestion and throttles its transmission rate, causing degraded end-to-end performance. This article provides an in-depth survey of various TCP enhancements which are specifically targeted for last-hop wireless environments. The objective is to review the performance issues of TCP variations, when employed in last-hop wireless networks, and to provide a categorized analysis of different existing solutions comparatively, as we all know that it is difficult to create a “one size fits all” TCP for last-hop wireless networks.

63 citations


Journal ArticleDOI
TL;DR: This survey chronicles the coding, modulation, and multiple access developments within the evolutional framework of cellular communication systems which spans early first generation (1G) to future fourth generation (4G) systems.
Abstract: Early cellular networks used analog frequency modulation for voice communication and frequency division multiple access to accommodate multiple users. Despite their utility, these networks were often unstable and provided poor quality. Over the past 25 years, robust coding, modulation, and multiple access schemes have contributed greatly to improved, ubiquitous cellular service. This survey chronicles the coding, modulation, and multiple access developments within the evolutional framework of cellular communication systems which spans early first generation (1G) to future fourth generation (4G) systems. EVOLUTION OF THE AIR INTERFACE OF CELLULAR COMMUNICATIONS SYSTEMS TOWARD 4G REALIZATION 1ST QUARTER 2006, VOLUME 8, NO. 1 www.comsoc.org/pubs/surveys 1553-877X The views expressed in this article are those of the authors and do not reflect the official policy or position of the United States Air Force, Department of Defense, or the U.S. Government.

Journal ArticleDOI
TL;DR: A survey on arrival EPs and service curves is provided to provide a comprehensive survey of existing work, which can yield useful insights, and help the development of new QoS metrics, mechanisms, and architectures for emerging network environments.
Abstract: Provisioning of quality of service (QoS) guarantees has become an increasingly important and challenging topic in the design of the current and the next-generation Internet. The class of envelope processes (EPs) is one of the key elements for many QoS provisioning mechanisms. An arrival EP A(τ) (or a service curve) bounds the cumulative traffic of a flow (or the cumulative service a flow receives) over any interval of length τ. Such bounds can be deterministic or probabilistic, and can be used for provisioning of deterministic or statistical service guarantees. In this article we provide a survey on arrival EPs and service curves. We provide an overview of various EPs proposed in the literature during the last 15 years and discuss their applications and performance in QoS provisioning. We aim to provide a big picture of the existing work. There is considerable research effort addressing QoS issues in resource-constrained access networks (such as wireless networks) and in the new multiprotocol label switching (MPLS) and peer-to-peer (P2P) networking paradigms. We aim to provide a comprehensive survey of existing work, which can yield useful insights, and help the development of new QoS metrics, mechanisms, and architectures for emerging network environments.


Journal ArticleDOI
TL;DR: A comprehensive survey of the handover algorithms in DVB-H is provided and a systematic evaluation and categorization approach is proposed based on the problems the algorithms solve and the hand over stages being focused on.
Abstract: Digital video broadcasting for handhelds (DVB-H) is a standard for broadcasting IP Datacast (IPDC) services to mobile handheld terminals. Based on the DVB-T standard, DVB-H adds new features such as time slicing, MPE-FEC, in-depth interleavers, mandatory cell id identifier, optional 4K-modulation mode and the use of 5 MHz bandwidth in addition to the usually used 6, 7, or 8 MHz raster. IPDC over DVB-H is proposed for ETSI to complement the DVB-H standard by combining IPDC and DVB-H in an end-to-end system. Handover in such unidirectional broadcasting networks is a novel issue. In the last few years since the birth of DVB-H technology, great attention has been given to the performance analysis of DVB-H mobile terminals. Handover is one of the main research topics for DVB-H in mobile scenarios. Better reception quality and greater power efficiency are considered to be the main targets of handover research for DVB-H. New algorithms for different handover stages in DVB-H have been the subject of recent research and are currently being studied. Further novel algorithms need to be designed to improve the mobile reception quality. This article provides a comprehensive survey of the handover algorithms in DVB-H. A systematic evaluation and categorization approach is proposed based on the problems the algorithms solve and the handover stages being focused on. Criteria are proposed and analyzed to facilitate designing better handover algorithms for DVB-H that have been identified from the research conducted by the authors.

Journal ArticleDOI
TL;DR: This article surveys the approaches that have been proposed in the past to address the jitter impairment in real-time voice communications, and particular attention is devoted to the techniques employing sophisticated speech quality models, which represent the latest advance in this field.
Abstract: Playout buffering is a key component in telephony over IP services. It allows the receiver to compensate network jitter and to resynchronize the received packets flows so as to achieve smooth voice decoding. The management of the playout buffer heavily influences the final quality of service (QoS), since the packet loss rate and total one-way delay depend upon it. In this article, starting from an analysis of the jitter impairment in real-time voice communications, we survey the approaches that have been proposed in the past to address this problem. A classification and a chronological timeline of strategies and breakthroughs are provided, with an analysis of interactions with other related areas. Particular attention is devoted to the techniques employing sophisticated speech quality models, which represent the latest advance in this field. The article ends with an analysis of the advantages and weaknesses of the proposed solutions. PLAYOUT BUFFERING IN IP TELEPHONY: A SURVEY DISCUSSING PROBLEMS AND APPROACHES 3RD QUARTER 2006, VOLUME 8, NO. 3 www.comsoc.org/pubs/surveys

Journal ArticleDOI
TL;DR: This work reviews typical algorithms and profiles their performance under various situations to study the influence of the number, the length, and the character distribution of the signatures on performance, and replaces their original algorithms with the most efficient ones in the profiling.
Abstract: The efficiency of string matching algorithms is essential for network content security applications, such as intrusion detection systems, anti-virus systems, and Web content filters. This work reviews typical algorithms and profiles their performance under various situations to study the influence of the number, the length, and the character distribution of the signatures on performance. This profiling can reveal the most efficient algorithm in each situation. A fast verification method for some string matching algorithms is also proposed. This work then analyzes the signature characteristics of three content security applications and replaces their original algorithms with the most efficient ones in the profiling. The improvement for both real and synthetic sample data is observed. For example, an open source anti-virus package, ClamAV, is five times faster after the revision. This work features comprehensive profiling results of typical string matching algorithms and observations of their application on network content security. The results can enlighten the choice of a proper algorithm in practical design.

Journal ArticleDOI
TL;DR: This article surveys the literature during the period of 1995‐2005 on accelerating the generation and delivery of dynamic Web content and introduces a research-charting semi-formal framework called the Caching Fragmentation Polymorphism (CFP) framework, within which it relates the surveyed approaches and depict their relationships.
Abstract: The shift from static to dynamic Web content has been dramatic. Dynamic Web content is facilitated by specialized cooperating component systems better known as content middlewares. Unlike static content, the generation and delivery of dynamic Web content introduce heavy a workload on content middlewares. To address this problem, numerous research approaches have been proposed in the literature, some of which are the driving force behind popular commercial systems, a fact that stresses the importance and applicability of this research area. This article surveys the literature during the period of 1995‐2005 on accelerating the generation and delivery of dynamic Web content. It classifies the proposed approaches into taxonomies based on their underlying methodologies and practices. In order to illustrate the evolution of research, we introduce a research-charting semi-formal framework called the Caching Fragmentation Polymorphism (CFP) framework, within which we relate the surveyed approaches and depict their relationships.