Showing papers in "IEEE Communications Magazine in 2007"
TL;DR: In this article, a statistical model based on empirical data is presented, and it is shown how to use this model for deriving access strategies for the coexistence of Bluetooth and WLAN.
Abstract: Dynamic spectrum access is a promising approach to alleviate the spectrum scarcity that wireless communications face today. In short, it aims at reusing sparsely occupied frequency bands while causing no (or insignificant) interference to the actual licensees. This article focuses on applying this concept in the time domain by exploiting idle periods between bursty transmissions of multi-access communication channels and addresses WLAN as an example of practical importance. A statistical model based on empirical data is presented, and it is shown how to use this model for deriving access strategies. The coexistence of Bluetooth and WLAN is considered as a concrete example
549 citations
TL;DR: This article discusses the basics of passive RFID technologies, with an emphasis on tags, for general readers and entry- level practitioners and offers a vision of the technology's future.
Abstract: This article discusses the basics of passive RFID technologies, with an emphasis on tags, for general readers and entry- level practitioners. Following a brief history of RFID, it describes the types of tags and their operation, and regulations and frequency ranges. It then presents representative applications and describes the major technical hurdles still to be overcome before the adoption of RFID can be widespread, and offers a vision of the technology's future.
423 citations
TL;DR: The trade-off between regulation and autonomy inherent in the design and performance of cognitive networks is examined through a simple example, which shows that the optimal amount of licensing is equal to the duty cycle of the traffic arrivals.
Abstract: Cognitive radios are promising solutions to the problem of overcrowded spectrum. In this article we explore the throughput potential of cognitive communication. Different interpretations of cognitive radio that underlay, overlay, and interweave the transmissions of the cognitive user with those of licensed users are described. Considering opportunistic communication as a baseline, we investigate the throughput improvements offered by the overlay methods. Channel selection techniques for opportunistic access such as frequency hopping, frequency tracking, and frequency coding are presented. The trade-off between regulation and autonomy inherent in the design and performance of cognitive networks is examined through a simple example, which shows that the optimal amount of licensing is equal to the duty cycle of the traffic arrivals
379 citations
TL;DR: The ecosystem emerging around ZigBee, and the enabling trends in that ecosystem, are described, which describe the ecosystem emergingaround Zigbee, and how to enable and manage that ecosystem.
Abstract: After around a decade of active research on wireless sensor networks, recent standards released are stimulating the development of commercial products. One of these standards is ZigBee. This article highlights some of the lessons from the field that went into the standard. It also describes the ecosystem emerging around Zigbee, and the enabling trends in that ecosystem. New areas of activity in the ZigBee standards body are highlighted as well
362 citations
TL;DR: To deploy IPTV services with a full quality of service (QoS) guarantee, many underlying technologies must be further studied.
Abstract: Internet protocol television (IPTV) will be the killer application for the next-generation Internet and will provide exciting new revenue opportunities for service providers. However, to deploy IPTV services with a full quality of service (QoS) guarantee, many underlying technologies must be further studied. This article serves as a survey of IPTV services and the underlying technologies. Technical challenges also are identified.
359 citations
Journal Article•
TL;DR: A statistical model based on empirical data is presented, and it is shown how to use this model for deriving access strategies and the coexistence of Bluetooth and WLAN is considered as a concrete example.
Abstract: Dynamic spectrum access is a promising approach to alleviate the spectrum scarcity that wireless communications face today. In short, it aims at reusing sparsely occupied frequency bands while causing no (or insignificant) interference to the actual licensees. This article focuses on applying this concept in the time domain by exploiting idle periods between bursty transmissions of multi-access communication channels and addresses WLAN as an example of practical importance. A statistical model based on empirical data is presented, and it is shown how to use this model for deriving access strategies. The coexistence of Bluetooth and WLAN is considered as a concrete example.
347 citations
TL;DR: A game theoretical overview of dynamic spectrum sharing from several aspects: analysis of network users' behaviors, efficient dynamic distributed design, and optimality analysis is provided.
Abstract: In order to fully utilize the scarce spectrum resources, with the development of cognitive radio technologies, dynamic spectrum sharing becomes a promising approach to increase the efficiency of spectrum usage. Game theoretical dynamic spectrum sharing has been extensively studied for more flexible, efficient, and fair spectrum usage through analyzing the intelligent behaviors of network users equipped with cognitive radio devices. This article provides a game theoretical overview of dynamic spectrum sharing from several aspects: analysis of network users' behaviors, efficient dynamic distributed design, and optimality analysis
327 citations
TL;DR: A new channel assignment scheme called MesTiC is described, which incorporates the mesh traffic pattern together with connectivity issues in order to minimize interference in multi- radio mesh networks.
Abstract: Next-generation wireless mobile communications will be driven by converged networks that integrate disparate technologies and services. The wireless mesh network is envisaged to be one of the key components in the converged networks of the future, providing flexible high- bandwidth wireless backhaul over large geographical areas. While single radio mesh nodes operating on a single channel suffer from capacity constraints, equipping mesh routers with multiple radios using multiple nonoverlap- ping channels can significantly alleviate the capacity problem and increase the aggregate bandwidth available to the network. However, the assignment of channels to the radio interfaces poses significant challenges. The goal of channel assignment algorithms in multiradio mesh networks is to minimize interference while improving the aggregate network capacity and maintaining the connectivity of the network. In this article we examine the unique constraints of channel assignment in wireless mesh networks and identify the key factors governing assignment schemes, with particular reference to interference, traffic patterns, and multipath connectivity. After presenting a taxonomy of existing channel assignment algorithms for WMNs, we describe a new channel assignment scheme called MesTiC, which incorporates the mesh traffic pattern together with connectivity issues in order to minimize interference in multi- radio mesh networks.
318 citations
TL;DR: An overview of existing work in multihop relaying research is presented, pointing out key research issues and their possible solutions, and a resource allocation framework for out-of- band relaying is presented.
Abstract: Recently, there has been increasing interest in integrating multihop relaying functionalities into cellular wireless networks. Multihop cellular networks can potentially enhance coverage, data rates, QoS performance in terms of call blocking probability, bit error rate, as well as QoS fairness for different users. However, in-depth investigations and careful system designs are required to exploit these potential advantages. Specifically, routing and resource allocation algorithms should be designed such that the maximum performance gain can be achieved. A number of different architectures, protocols, and analytical models for MCNs have been proposed in the literature where different system aspects were investigated. This article aims to present an overview of existing work in this area, pointing out key research issues and their possible solutions. Also, we present a resource allocation framework for out-of- band relaying. The throughput enhancement due to the proposed framework is demonstrated through numerical results.
276 citations
TL;DR: DFH community, as described in this article, is a mechanism that coordinates multiple WRAN cells operating in the DFH mode, such that efficient frequency usage and reliable channel sensing are achieved.
Abstract: One of the key challenges of the emerging cognitive radio-based IEEE 802.22 wireless regional area networks (WRANs) is to address two apparently conflicting requirements: ensuring QoS satisfaction for WRAN services while providing reliable spectrum sensing for guaranteeing licensed user protection. To perform reliable sensing, in the basic operation mode on a single frequency band (non-hopping mode), one must allocate quiet times, that is, periodically interrupt data transmission that could impair the QoS of WRAN. This critical issue can be addressed by an alternative operation mode proposed in 802.22 called dynamic frequency hopping (DFH), where WRAN data transmission is performed in parallel with spectrum sensing without interruptions. DFH community, as described in this article, is a mechanism that coordinates multiple WRAN cells operating in the DFH mode, such that efficient frequency usage and reliable channel sensing are achieved. The key idea of DFH community is that neighboring WRAN cells form cooperating communities that coordinate their DFH operations
270 citations
TL;DR: It is shown that, although pure general-purpose MANET (mobile ad hoc networks) does not yet exist in the real world, the multihop ad hoc networking paradigm was successfully applied in several classes of networks that are penetrating the mass market.
Abstract: In this article we show that, although pure general-purpose MANET (mobile ad hoc networks) does not yet exist in the real world, the multihop ad hoc networking paradigm was successfully applied in several classes of networks that are penetrating the mass market. We present as examples mesh, opportunistic, vehicular, and sensor networks, where the multi-hop ad hoc paradigm is applied in a pragmatic way to extend the Internet and/or to support well-defined application requirements. We contrast these successful areas of ad hoc networking to the lack of impact of pure general-purpose MANET, demonstrating how a more pragmatic approach is a winner
TL;DR: This article reviews the basic principles behind mobile ad hoc networks (MANET) and critically discusses approximately ten years of research in this field and point out the limits of MANET research.
Abstract: This article reviews the basic principles behind mobile ad hoc networks (MANET) and critically discusses approximately ten years of research in this field We summarize the main achievements and point out the limits of MANET research This research was conducted under the assumption that the networks mainly will be used for large-scale general consumer applications, and nodes would be ubiquitous, thus reasonably dense and active Both assumptions do not reflect reality and certainly would not be true in an initial phase of deployment A lack of realism regarding the objective of MANET coupled with a lack of realism during the design of MANET are the main causes of MANET running a high risk of failure
TL;DR: This article provides an introduction to the FOCALE autonomic network management architecture, which is designed to address challenges facing communications networks using traditional approaches that rely on human monitoring and intervention to ensure they operate within desired bounds.
Abstract: As communications networks become increasingly dynamic, heterogeneous, less reliable, and larger in scale, it becomes difficult, if not impossible, to effectively manage these networks using traditional approaches that rely on human monitoring and intervention to ensure they operate within desired bounds. Researchers and practitioners are pursuing the vision of autonomic network management, which we view as the capability of network entities to self-govern their behavior within the constraints of business goals that the network as a whole seeks to achieve. However, applying autonomic principles to network management is challenging for a number of reasons, including: (1) A means is required to enable business rules to determine the set of resources and/or services to be provided. (2) Contextual changes in the network must be sensed and interpreted, because new management policies may be required when context changes. (3) As context changes, it may be necessary to adapt the management control loops that are used to ensure that system functionality adapts to meet changing user requirements, business goals, and environmental conditions. (4) A means is required to verify modeled data and to add new data dynamically so that the system can learn and reason about itself and its environment. This article provides an introduction to the FOCALE autonomic network management architecture, which is designed to address these challenges.
TL;DR: The reasons why the PON as a general architecture is so important are reviewed, and the technologies used to implement this architecture are outlined, including the G- and E-PON systems being deployed today.
Abstract: Passive optical networks are the most important class of fiber access systems in the world today. This article first reviews the reasons why the PON as a general architecture is so important. We then outline in some depth the technologies used to implement this architecture, including the G-PON and E-PON systems being deployed today, and the advanced PON systems that provide the evolution path to ever higher bandwidths
TL;DR: In this article, the authors provide design perspectives on relay deployment, spectrum allocation, and end-to-end optimization of certain QoS measures such as throughput, coverage, reliability, and robustness.
Abstract: We summarize capacity results to show merits of multihop relaying in broadband cellular mesh networks. Under the guidance of these results, we provide design perspectives on relay deployment, spectrum allocation, and end-to-end optimization of certain QoS measures such as throughput, coverage, reliability, and robustness. We conclude with an overview of recent standardization activities and remarks on remaining open problems and design challenges.
TL;DR: The interlinked technical and economic issues associated with markets for DSA-based wireless services are examined to make technical and policy recommendations supporting the commercial success of DSA technology.
Abstract: Rapid progress is being made in the technology for dynamic spectrum access (DSA) radio systems. However, the structure and dynamics of the wireless services market must also evolve for DSA to succeed. This article examines the interlinked technical and economic issues associated with markets for DSA-based wireless services. We use this analysis to make technical and policy recommendations supporting the commercial success of DSA technology
TL;DR: In this paper, the authors proposed four broadband access architectures to integrate EPON and WiMAX technologies, which can take advantage of the bandwidth benefit of fiber communications, and the mobile and non-line-of-sight features of wireless communications.
Abstract: EPON and WiMAX are two promising broadband access technologies for new-generation wired and wireless access. Their complementary features motivate interest in using EPON as a backhaul to connect multiple dispersed WiMAX base stations. In this article we propose four broadband access architectures to integrate EPON and WiMAX technologies. The integrated architectures can take advantage of the bandwidth benefit of fiber communications, and the mobile and non-line-of-sight features of wireless communications. Based on these integrated architectures, we elaborate on related control and operation issues to address the benefits gained by this integration. Integration of EPON and WiMAX enables fixed mobile convergence, and is expected to significantly reduce overall design and operational costs for new-generation broadband access networks.
TL;DR: This article proposes a multicast and broadcast service (MBS) architecture for WiMAX that is based on MBMS and enhances the MBS architecture for mobile WiMAX to overcome the shortcoming of limited video broadcast performance over the baseline MBS model.
Abstract: Multimedia stream service provided by broadband wireless networks has emerged as an important technology and has attracted much attention. An all-IP network architecture with reliable high-throughput air interface makes orthogonal frequency division multiplexing access (OFDMA)-based mobile worldwide interoperability for microwave access (mobile WiMAX) a viable technology for wireless multimedia services, such as voice over IP (VoIP), mobile TV, and so on. One of the main features in a WiMAX MAC layer is that it can provide'differentiated services among different traffic categories with individual QoS requirements. In this article, we first give an overview of the key aspects of WiMAX and describe multimedia broadcast multicast service (MBMS) architecture of the 3GPP. Then, we propose a multicast and broadcast service (MBS) architecture for WiMAX that is based on MBMS. Moreover, we enhance the MBS architecture for mobile WiMAX to overcome the shortcoming of limited video broadcast performance over the baseline MBS model. We also give examples to demonstrate that the proposed architecture can support better mobility and offer higher power efficiency.
TL;DR: A cross-layer design framework based on a novel two-level superposition coded multicasting (SCM) scheme is introduced and simulation results show that much improved video quality is achievable with this approach.
Abstract: The advances in broadband Internet access and scalable video technologies have made it possible for Internet Protocol television (IPTV) to become the next killer application for modern Internet carriers in metropolitan areas. With the recent release of IEEE 802.16d/e (worldwide interoperability for microwave access or WiMAX), broadband wireless access (BWA) is envisioned to further extend IPTV services to a new application scenario with wireless and mobility dimensions. It is a very strategic but challenging leverage for a carrier to glimpse the potential of IPTV by using WiMAX as the access network. Challenges are posed for IPTV over WiMAX due to multicasting under a diversity of fading conditions. A cross-layer design framework based on a novel two-level superposition coded multicasting (SCM) scheme is introduced. Simulation results show that much improved video quality is achievable with our approach.
TL;DR: An overview of the state-of-the-art mobile WiMAX technology and its development is provided, focusing on QoS provisioning and mobile WiMax specification.
Abstract: The IEEE 802.16 standard, commonly known as WiMAX, is the latest technology that has promised to offer broadband wireless access over long distance. Since 2001 WiMAX has evolved from 802.16 to 802.16d for fixed wireless access, and to the new IEEE 802.16e standard with mobility support. In this article we provide an overview of the state-of-the-art mobile WiMAX technology and its development. We focus our discussion on QoS provisioning and mobile WiMAX specification.
TL;DR: Five important aspects in the use of WiFi for rural connectivity: network planning and deployment, network protocols, network management and operations, power savings, and applications and services are discussed.
Abstract: Access to communication can play a pivotal role in the socio-economic development of rural regions in the third world. For affordability, the choice of technology to achieve this is a significant aspect. We have chosen IEEE 802.11 as a cost-effective technology to provide rural connectivity in the context of two projects in India: digital Gangetic plains (DGP) and Ashwini. This article presents our experiences with these two projects and discusses five important aspects in the use of WiFi for rural connectivity: network planning and deployment, network protocols, network management and operations, power savings, and applications and services
TL;DR: In this article, an integrated WiMAX/WiFi network for such an application where the licensed WiMAX spectrum is shared by the WiFi access points/routers to provide Internet connectivity to mobile WiFi users is considered.
Abstract: Broadband wireless access networks based on WiMAX can provide backhaul support for mobile WiFi hotspots. We consider an integrated WiMAX/WiFi network for such an application where the licensed WiMAX spectrum is shared by the WiFi access points/routers to provide Internet connectivity to mobile WiFi users. The WiMAX backbone network and WiFi hotspots are operated by different service providers. Issues such as protocol adaptation, quality of service support, and pricing for bandwidth sharing that are related to integration of these networks are discussed. In addition, we propose a model for optimal pricing for bandwidth sharing in an integrated WiMAX/WiFi network. A Stackelberg leader-follower game is formulated to obtain the optimal pricing solution for bandwidth sharing. Performance evaluation results reveal some interesting insights into the problem
TL;DR: This article analyzes what is available to the end user in terms of P2P video-streaming products and determines which of these are the most promising for IPTV and content distribution companies.
Abstract: The great success of P2P systems for the purpose of file-sharing set the path to the next killer application on the Internet, P2P video streaming. Although it solves scalability issues, P2P technology experiences problems of a long start time and churn-induced instability that can greatly affect the user experience. Moreover, technical and business solutions for digital rights management are still under investigation. Great efforts are underway in both academia and industry to solve these problems, whose solution will offer a scalable, affordable, and legal TV-quality-like broadcast of content. In this article, we analyze what is available to the end user in terms of P2P video-streaming products and determine which of these are the most promising for IPTV and content distribution companies. In the following, we offer: (1) A survey of the available architectures. (2) A set of experiments on a popular peer-to-peer system, SopCast. (3) Guidelines for large scale deployment.
TL;DR: A cellular trackside solution for providing broadband multimedia services to train passengers by using a radio-over-fiber network in combination with moving cells forms the base of this realization.
Abstract: Nowadays, combining high-bandwidth connections (e.g., 5 Mb/s/user) and fast-moving users (e.g., on a train at 300 km/h) while keeping a sufficient level of QoS is still an unsolved bottleneck. In this article we propose a cellular trackside solution for providing broadband multimedia services to train passengers. A radio-over-fiber network in combination with moving cells forms the base of this realization
Journal Article•
TL;DR: An overview of the state-of-the-art mobile WiMAX technology and its development is provided, focusing on QoS provisioning and mobile WiMax specification.
Abstract: The IEEE 802.16 standard, commonly known as WiMAX, is the latest technology that has promised to offer broadband wireless access over long distance. Since 2001 WiMAX has evolved from 802.16 to 802.16d for fixed wireless access, and to the new IEEE 802.16e standard with mobility support. In this article we provide an overview of the state-of-the-art mobile WiMAX technology and its development. We focus our discussion on QoS provisioning and mobile WiMAX specification.
TL;DR: Although a prerequisite for OCDMA, optical coding distinguishes itself from OCDMA through major applications where codes are not applied to data and carry network-level information other than user identity.
Abstract: We survey the current trends in OCDMA and optical coding through their applications. Although a prerequisite for OCDMA, optical coding distinguishes itself from OCDMA through major applications where codes are not applied to data and carry network-level information other than user identity. After introducing the principles of coding, we discuss OCDMA and its applications, particularly OCDMA PON. Optical coding and its applications are then reviewed.
TL;DR: The workshop identified several topic areas, including management architectures, distributed real-time monitoring, data analysis and visualization, ontologies, economic aspects of management, uncertainty and probabilistic approaches, as well as understanding the behavior of managed systems.
Abstract: Although network management has always played a key role for industry, it only recently received a similar level of attention from many research communities, accelerated by funding opportunities from new initiatives, including the FP7 Program in Europe and GENI/FIND in the United States. Work is ongoing to assess the state of the art and identify the challenges for future research in the field, and this article contributes to this discussion. It presents major findings from a two-day workshop organized jointly by the IRTF/NMRG and the EMANICS Network of Excellence, at which researchers, operators, vendors, and technology developers discussed the research directions to be pursued over the next five years. The workshop identified several topic areas, including management architectures, distributed real-time monitoring, data analysis and visualization, ontologies, economic aspects of management, uncertainty and probabilistic approaches, as well as understanding the behavior of managed systems.
TL;DR: A set of frameworks based on patient life cycle and time-and-motion perspectives for how RFID can be leveraged atop existing information systems to offer many benefits for patient care and hospital operations are developed.
Abstract: The application of Radio Frequency Identification (RFID) to patient care in hospitals and healthcare facilities has only just begun to be accepted. This article develops a set of frameworks based on patient life cycle and time-and-motion perspectives for how RFID can be leveraged atop existing information systems to offer many benefits for patient care and hospital operations. It examines how patients are processed from admission to discharge, and considers where RFID can be applied. From a time-and-motion perspective, it shows how hospitals can apply RFID in three ways: fixed RFID readers interrogate mobile objects; mobile, handheld readers interrogate fixed objects; and mobile, handheld readers interrogate mobile objects. Implemented properly, RFID can significantly aid the medical staff in performing their duties. It can greatly reduce the need for manual entry of records, increase security for both patient and hospital, and reduce errors in administering medication. Hospitals are likely to encounter challenges, however, when integrating the technology into their day-to-day operations. What we present here can help hospital administrators determine where RFID can be deployed to add the most value.
Journal Article•
TL;DR: The XG Radio system uses dynamic spectrum access technology to determine locally unused spectrum, and then operates on these channels without causing interference to existing non-cooperative users.
Abstract: The XG Radio system uses dynamic spectrum access technology to determine locally unused spectrum, and then operates on these channels without causing interference to existing non-cooperative users. In August 2006 the XG Radio system was field tested at Fort A.P. Hill, Virginia, in the laboratory, and at field locations in Northern Virginia. There were three major test criteria: to cause no harm (avoid interference), to work (form and maintain connected networks), and to add value (efficiently use spectrum). This article defines the test metrics for fulfillment of these criteria, and describes the test results.
TL;DR: The obstacles faced in achieving robust detection and avoidance with an on-chip implementation of basic DAA functionality are described and measurement results for operation of a single UWB device with a WiMAX system are presented.
Abstract: Cognitive radios have been advanced as a technology for the opportunistic use of underutilized spectrum wherein secondary devices sense the presence of the primary user and use the spectrum only if it is deemed empty. Spectral cognition of this form can also be used by regulators to facilitate the dynamic coexistence of different service types. An example of this is the operation of ultra-wideband devices in WiMAX bands: UWB devices must detect and avoid WiMAX devices in certain regulatory domains. In this article we start by discussing various options for detection and avoidance. We then describe the obstacles faced in achieving robust detection and avoidance with an on-chip implementation of basic DAA functionality. Finally, we present measurement results for operation of a single UWB device with a WiMAX system. This interaction also highlights the problem of dealing with listen before speak primaries where secondary transmission could interfere by blocking the primary's access to the medium.