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Showing papers in "IEEE Wireless Communications in 2004"


Journal ArticleDOI
TL;DR: A survey of state-of-the-art routing techniques in WSNs is presented and the design trade-offs between energy and communication overhead savings in every routing paradigm are studied.
Abstract: Wireless sensor networks consist of small nodes with sensing, computation, and wireless communications capabilities. Many routing, power management, and data dissemination protocols have been specifically designed for WSNs where energy awareness is an essential design issue. Routing protocols in WSNs might differ depending on the application and network architecture. In this article we present a survey of state-of-the-art routing techniques in WSNs. We first outline the design challenges for routing protocols in WSNs followed by a comprehensive survey of routing techniques. Overall, the routing techniques are classified into three categories based on the underlying network structure: flit, hierarchical, and location-based routing. Furthermore, these protocols can be classified into multipath-based, query-based, negotiation-based, QoS-based, and coherent-based depending on the protocol operation. We study the design trade-offs between energy and communication overhead savings in every routing paradigm. We also highlight the advantages and performance issues of each routing technique. The article concludes with possible future research areas.

4,701 citations


Journal ArticleDOI
TL;DR: This article discusses the consequences of this fact with regard to the design space of wireless sensor networks by considering its various dimensions and justifies the view by demonstrating that specific existing applications occupy different points in thedesign space.
Abstract: In the recent past, wireless sensor networks have found their way into a wide variety of applications and systems with vastly varying requirements and characteristics. As a consequence, it is becoming increasingly difficult to discuss typical requirements regarding hardware issues and software support. This is particularly problematic in a multidisciplinary research area such as wireless sensor networks, where close collaboration between users, application domain experts, hardware designers, and software developers is needed to implement efficient systems. In this article we discuss the consequences of this fact with regard to the design space of wireless sensor networks by considering its various dimensions. We justify our view by demonstrating that specific existing applications occupy different points in the design space.

1,666 citations


Journal ArticleDOI
Hao Yang1, Haiyun Luo1, Fan Ye1, Songwu Lu1, Lixia Zhang1 
TL;DR: The security issues related to this problem are identified, the challenges to security design are discussed, and the state-of-the-art security proposals that protect the MANET link- and network-layer operations of delivering packets over the multihop wireless channel are reviewed.
Abstract: Security has become a primary concern in order to provide protected communication between mobile nodes in a hostile environment. Unlike the wireline networks, the unique characteristics of mobile ad hoc networks pose a number of nontrivial challenges to security design, such as open peer-to-peer network architecture, shared wireless medium, stringent resource constraints, and highly dynamic network topology. These challenges clearly make a case for building multifence security solutions that achieve both broad protection and desirable network performance. In this article we focus on the fundamental security problem of protecting the multihop network connectivity between mobile nodes in a MANET. We identify the security issues related to this problem, discuss the challenges to security design, and review the state-of-the-art security proposals that protect the MANET link- and network-layer operations of delivering packets over the multihop wireless channel. The complete security solution should span both layers, and encompass all three security components of prevention, detection, and reaction.

970 citations


Journal ArticleDOI
TL;DR: In this article, the current state of the art for mobility management in next-generation all-IP-based wireless systems is presented, and the previously proposed solutions based on different layers are reviewed, and their qualitative comparisons are given.
Abstract: Next-generation wireless systems are envisioned to have an IP-based infrastructure with the support of heterogeneous access technologies. One of the research challenges for next generation all-IP-based wireless systems is the design of intelligent mobility management techniques that take advantage of IP-based technologies to achieve global roaming among various access technologies. Next-generation wireless systems call for the integration and interoperation of mobility management techniques in heterogeneous networks. In this article the current state of the art for mobility management in next-generation all-IP-based wireless systems is presented. The previously proposed solutions based on different layers are reviewed, and their qualitative comparisons are given. A new wireless network architecture for mobility management is introduced, and related open research issues are discussed in detail.

672 citations


Journal ArticleDOI
TL;DR: This article presents a tutorial on the design and performance issues for vertical handoff in an envisioned multinetwork fourth-generation environment, including new techniques for dynamic handoff decision and detection algorithms and context-aware radio link transfer.
Abstract: Revolutionary drivers for 4G include a push toward universal wireless access and ubiquitous computing through seamless personal and terminal mobility. One of the major challenges for seamless mobility is the criterion of a vertical handoff protocol: a handoff protocol for users that move between different types of networks. Traditional operations for handoff detection policies, decision metrics, and radio link transfer are not able to adapt to dynamic handoff criteria or react to user inputs and changing network availabilities. Nor are they able to deliver context-aware services or ensure network interoperability. Thus, new techniques are needed to manage user mobility between different types of networks. This article presents a tutorial on the design and performance issues for vertical hand-off in an envisioned multinetwork fourth-generation environment. Various network architectures and technologies for 3G and beyond are described, including wireless LANs, cellular, satellite, and Mobile IP. Then the problem of vertical handoff is defined in the context of such a diverse network environment. Finally, research efforts to resolve the open problems are explored, including new techniques for dynamic handoff decision and detection algorithms and context-aware radio link transfer.

634 citations


Journal ArticleDOI
TL;DR: The authors discuss issues and consider mechanisms to achieve secure communication in wireless sensor networks and suggest careful decisions and trade-offs among various security measures.
Abstract: Sensor networks are expected to play an essential role in the upcoming age of pervasive computing. Due to their constraints in computation, memory, and power resources, their susceptibility to physical capture, and use of wireless communications, security is a challenge in these networks. The scale of deployments of wireless sensor networks require careful decisions and trade-offs among various security measures. The authors discuss these issues and consider mechanisms to achieve secure communication in these networks.

611 citations


Journal ArticleDOI
TL;DR: A survey on the work that has been done in the area of intrusion detection in mobile ad hoc networks finds that there is a need to complement traditional security mechanisms with efficient intrusion detection and response.
Abstract: Intrusion detection has, over the last few years, assumed paramount importance within the broad realm of network security, more so in the case of wireless ad hoc networks. These are networks that do not have an underlying infrastructure; the network topology is constantly changing. The inherently vulnerable characteristics of wireless ad hoc networks make them susceptible to attacks, and it may be too late before any counter action can take effect. Second, with so much advancement in hacking, if attackers try hard enough they will eventually succeed in infiltrating the system. This makes it important to constantly (or at least periodically) monitor what is taking place on a system and look for suspicious behavior. Intrusion detection systems (IDSs) do just that: monitor audit data, look for intrusions to the system, and initiate a proper response (e.g., email the systems administrator, start an automatic retaliation). As such, there is a need to complement traditional security mechanisms with efficient intrusion detection and response. In this article we present a survey on the work that has been done in the area of intrusion detection in mobile ad hoc networks.

421 citations


Journal ArticleDOI
Kristin E. Lauter1
TL;DR: An overview of elliptic curves and their use in cryptography is provided, focusing on the performance advantages to be obtained in the wireless environment by using elliptic curve cryptography instead of a traditional cryptosystem like RSA.
Abstract: This article provides an overview of elliptic curves and their use in cryptography. The focus is on the performance advantages to be obtained in the wireless environment by using elliptic curve cryptography instead of a traditional cryptosystem like RSA. Specific applications to secure messaging and identity-based encryption are discussed.

406 citations


Journal ArticleDOI
TL;DR: This article surveys 802.11 QoS schemes, including service differentiation in the MAC layer, admission control and bandwidth reservation in MAC and higher layers, and link adaptation in the physical layer, designed to meet challenges by providing the necessary enhancements for the required QoS.
Abstract: Developed as a simple and cost-effective wireless technology for best effort services, IEEE 802.11 has gained popularity at an unprecedented rate. However, due to the lack of built-in quality of service support, IEEE 802.11 experiences serious challenges in meeting the demands of multimedia services and applications. This article surveys 802.11 QoS schemes, including service differentiation in the MAC layer, admission control and bandwidth reservation in MAC and higher layers, and link adaptation in the physical layer, designed to meet these challenges by providing the necessary enhancements for the required QoS. Furthermore, the article addresses issues that arise when end-to-end QoS has to be guaranteed in today's pervasive heterogeneous wired-cum-wireless networks. Among these challenges, protocol interoperability, multihop scheduling, full mobility support, and seamless vertical handoff among multiple mobile/wireless interfaces are specifically addressed.

316 citations


Journal ArticleDOI
TL;DR: This article provides a domain-structured edge-to-edge view for the network control to embrace the heterogeneity arising from the different network control technologies, and aims for an instant network composition to allow rapid adaptation of the network domain topology as required for moving networks.
Abstract: In this article we present a new networking concept referred to as ambient networks, which aims to enable the cooperation of heterogeneous networks belonging to different operator or technology domains. We aim to provide a domain-structured edge-to-edge view for the network control to embrace the heterogeneity arising from the different network control technologies. In this way, it appears as homogeneous to the users of the network services. We aim for an instant network composition to allow rapid adaptation of the network domain topology as required for moving networks. This new view of network composition allows us to treat the communication endpoints as a special case of network domains as well. We introduce the ambient control space, which enables the ambient networks concept and introduce its main features. Two ambient control space functions, media delivery and generic link layer, are presented in more detail. AMBIENT NETWORKS: AN ARCHITECTURE FOR COMMUNICATION NETWORKS BEYOND 3G

296 citations


Journal ArticleDOI
TL;DR: The proposed SCTP-based vertical handover scheme does not require the addition of components such as home/foreign agents or a SIP server to existing networks and provides a network-independent solution preferred by service providers.
Abstract: This article proposes a new method to facilitate seamless vertical handover between wide area cellular data networks such as UMTS and WLANs using the stream control transmission protocol (SCTP). The multihoming capability and dynamic address configuration extension of SCTP are applied in UMTS/WLAN overlay architecture to decrease handover delay and improve throughput performance. Unlike techniques based on mobile IP or session initiation protocol, the SCTP-based vertical handover scheme does not require the addition of components such as home/foreign agents or a SIP server to existing networks. Therefore, the proposed scheme provides a network-independent solution preferred by service providers. Performance evaluations are presented to demonstrate the effectiveness of the proposed scheme.

Journal ArticleDOI
TL;DR: A novel data structure, the neighbor graph, that dynamically captures the mobility topology of a wireless network is introduced and it is shown how neighbor graphs can be utilized to obtain a 99 percent reduction in the authentication time of an IEEE 802.11 handoff.
Abstract: User mobility in wireless data networks is increasing because of technological advances, and the desire for voice and multimedia applications. These applications, however, require that handoffs between base stations (or access points) be fast to maintain the quality of the connections. In this article we introduce a novel data structure, the neighbor graph, that dynamically captures the mobility topology of a wireless network. We show how neighbor graphs can be utilized to obtain a 99 percent reduction in the authentication time of an IEEE 802.11 handoff (full EAP-TLS) by proactively distributing necessary key material one hop ahead of the mobile user. We also present a reactive method for fast authentication that requires only firmware changes to access points and hence can easily be deployed on existing wireless networks.

Journal ArticleDOI
Apostolis K. Salkintzis1
TL;DR: This article proposes and discusses some novel architectures able to provide internetworking between WLAN and 3G networks, and meet the requirements of the most common internetworking scenarios.
Abstract: The intense wireless LAN standardization and R&D activities worldwide, combines with the recent successful deployment of WLANs, provide prime evidence that WLAN technology will play a key role in the fourth generation of mobile data networks. In this context, there is a strong need to integrate WLANs with 3G mobile data networks and develop hybrid mobile data networks capable of ubiquitous data services and very high data rates in strategic locations. This article addresses this need by proposing and discussing some novel architectures able to provide internetworking between WLAN and 3G networks, and meet the requirements of the most common internetworking scenarios. These architectures can enable 3G subscribers to benefit from high-throughput IP connectivity in hotspots and also to attain service roaming across several radio access technologies, such as IEEE 802.11, HiperLan/2, ULTRAN, and GERAN.

Journal ArticleDOI
TL;DR: It is shown that a tightly integrated set of networking protocols is a good solution to reach the target of highly energy-efficient WSNs and combines medium access organization with routing.
Abstract: This article presents a cross-layered approach for networking in wireless sensor networks. WSNs differ greatly from traditional ad hoc wireless networks and therefore require the use of new types of network protocols that are energy-efficient to ensure a node lifetime of several years on a single battery and can operate without assistance of central managers in a dynamic network topology. We show that a tightly integrated set of networking protocols is a good solution to reach the target of highly energy-efficient WSNs. Our approach combines medium access organization with routing.

Journal ArticleDOI
TL;DR: A framework for further enhancements of the traditional IP- based protocol stack to meet current and future requirements is described and a first solution involving cross-layer design is proposed.
Abstract: The classical TCP/IP layered protocol archi- tecture is beginning to show signs of age. In order to cope with problems such as the poor performance of wireless links and mobile termi- nals, including the high error rate of wireless network interfaces, power saving requirements, quality of service, and an increasingly dynamic network environment, a protocol architecture that considers cross-layer interactions seems to be required. This article describes a framework for further enhancements of the traditional IP- based protocol stack to meet current and future requirements. Known problems associated with the strictly layered protocol architecture are summarized and classified, and a first solution involving cross-layer design is proposed.

Journal ArticleDOI
TL;DR: A novel integrated WWAN/WLAN two-hop-relay architecture is proposed that both enhances the system capacity of existing WWAN systems and extends the system coverage of WLAN terminals.
Abstract: Next-generation wireless systems (4G and beyond) are envisioned to provide ubiquitous high-speed access over heterogeneous radio technologies. The integration of cellular WWANs and WLANs has drawn considerable attention from the research and commercial communities (e.g., 3G+802.11). Emerging dualmode mobile terminals could provide flexibility and system performance enhancement by providing seamless roaming between WWANs and WLANs. In this article we propose a novel integrated WWAN/WLAN two-hop-relay architecture that both enhances the system capacity of existing WWAN systems and extends the system coverage of WLAN terminals. The proposed two-hop-relay architecture can be considered as a system-level macro diversity technique that utilizes temporal channel quality variation to achieve increased system capacity. Significant capacity gain is achieved with the proposed twohop-relay architecture in both a fixed-rate uplink CDMA system and a variable data rate downlink HDR-like system.

Journal ArticleDOI
Yang Xiao1
TL;DR: Both the contention-based and contention-free centrally controlled channel access mechanisms are introduced by describing not only the MAC protocol operations and parameters, but also the call admission techniques and scheduling algorithm that have been designed for IEEE 802.11e.
Abstract: This article introduces the emerging IEEE 802.11e standard to support quality of service at the medium access control layer. Both the contention-based and contention-free centrally controlled channel access mechanisms are introduced by describing not only the MAC protocol operations and parameters, but also the call admission techniques and scheduling algorithm that have been designed for IEEE 802.11e. Finally, we provide simulation results aimed to highlight the capability of the EDCF to differentiate the traffic classes.

Journal ArticleDOI
I. Stojmenovic1
TL;DR: Three approaches to guarantee delivery in a geocasting problem, based on depth-first search of the face tree and traversal of all faces that intersect the border of the geocast region, are described for the first time.
Abstract: In a geocasting problem, a message is sent from one node to all the nodes located in a designated region. For example, a monitoring center needs to contact all active sensors within a monitored area to either gather data from them periodically or provide its location to sensors covering a certain area for event reporting. Intelligent flooding methods exist for this task when all active sensors belong to the monitored area. However, when a particular area containing only a small subset of active sensors needs to be monitored, the problem reduces to geocasting. Most existing geocasting solutions are shown not to guarantee delivery. We describe three approaches to guarantee delivery. Two of them are face traversal schemes, based on depth-first search of the face tree and traversal of all faces that intersect the border of the geocasting region, respectively. In the entrance zone multicasting-based approach, the monitoring center divides the entrance ring of a geocast region into zones of diameter equal to the transmission radius. The problem is decomposed into multicasting toward the center of each zone, and flooding from these nodes. Improvements to all methods can be made by applying neighbor or area dominating sets and coverage, and converting nodes that are not selected to sleep mode. All solutions that guarantee delivery are reported here for the first time (except a message inefficient version of the face tree traversal scheme).

Journal ArticleDOI
K. Jain1
TL;DR: This article provides a simple security protocol against a wiretapping attack based on the network topology, and shows that an attacker can get any meaningful information only by wiretapping those links that are necessary for the communication between the sender and the receiver.
Abstract: In wireless networks, an attacker can tune a receiver and tap the communication between two nodes. Whether or not some meaningful information is obtained by tapping a wireless connection depends the security protocols used. One may use cryptographic techniques to secure the communications. In this article we discuss an alternate way of securing the communication between two nodes. We provide a simple security protocol against a wiretapping attack based on the network topology. Although we study the problem from a theoretical perspective, our protocol is easily implementable. Our protocol is at least as secure as any other protocol against these attacks. We show that an attacker can get any meaningful information only by wiretapping those links that are necessary for the communication between the sender and the receiver. We use techniques from network encoding. Our protocol works for any network topology, including cycle networks. We note here that acyclicity is the main assumption in much of the network encoding literature.

Journal ArticleDOI
Xia Gao1, Gang Wu1, T. Miki1
TL;DR: The state-of-the-art QoS techniques and standardization activities are summarized, important challenges in building a ubiquitous QoS framework over the heterogeneous environment are examined, and aQoS framework integrating a three-plane network infrastructure and a unified terminal cross-layer adaptation platform is proposed to provide seamless support for future applications.
Abstract: The remarkable advances in information technologies bring a heterogeneous environment for mobile users and service providers. This heterogeneity exists in wireless access technologies, networks, user terminals, applications, service providers, and so on. The ability to provide seamless and adaptive quality of service in such a heterogeneous environment is key to the success of next-generation wireless communications systems. There has been a considerable amount of QoS research recently. However, the main part of this research has been in the context of individual architectural components, and much less progress has been made in addressing the issue of an overall QoS architecture for the mobile Internet. This article first summarizes the state-of-the-art QoS techniques and standardization activities, then examines in detail important challenges in building a ubiquitous QoS framework over the heterogeneous environment, and finally proposes a QoS framework integrating a three-plane network infrastructure and a unified terminal cross-layer adaptation platform to provide seamless support for future applications.

Journal ArticleDOI
TL;DR: A context transfer solution for AAA is proposed to enhance the multilayer mobility management scheme by avoiding the additional delay introduced by AAA security procedures.
Abstract: This article presents a multilayer mobility management scheme for all-IP networks where local mobility movements (micro-mobility) are handled separately from global movements (macro-mobility). Furthermore, a hybrid scheme is proposed to handle macro-mobility (mobile IP for non-real-time services and SIP for real-time services). The internetworking between micromobility and macro-mobility is implemented at an entity called the enhanced mobility gateway. Both qualitative and quantitative results have demonstrated that the performance of the proposed mobility management is better than existing schemes. Furthermore, a context transfer solution for AAA is proposed to enhance the multilayer mobility management scheme by avoiding the additional delay introduced by AAA security procedures.

Journal ArticleDOI
Geir M. Køien1
TL;DR: The first generation of cellular mobile communications systems contained few if any security measures to protect the system operator and users, but a serious effort has been made to create a consistent security architecture based on the threats and risks a 3G system faces.
Abstract: The first generation of cellular mobile communications systems contained few if any security measures to protect the system operator and users. The second generation generally did a lot better, and contained entity authentication and confidentiality protection. Although this was a major improvement, security protection in the second generation left a lot to be desired. With the advent of 3G mobile systems a serious effort has been made to create a consistent security architecture based on the threats and risks a 3G system faces.

Journal ArticleDOI
TL;DR: This study reviews the different design techniques in the hierarchical architecture and some analytical tools to study the performance of these designs.
Abstract: Third-generation wireless communication faces the challenges of rapidly increasing mobile user demand against limited radio bandwidth. Splitting cells into smaller cells can reduce the frequency reuse distance to improve network capacity within a certain area. Other than increasing the cost of the fixed infrastructure, cell splitting also causes the problem of increasing handoff rate and event the handoff failure rate when high-speed users roam in the network. To solve this problem, larger cells are overlaid on these smaller cells, and different classes of users (usually classified by speed) are initially assigned to the proper types of cells (i.e., proper tiers). We call this kind of cellular network a hierarchical cellular network. In this study, we review the different design techniques in the hierarchical architecture and some analytical tools to study the performance of these designs.

Journal ArticleDOI
TL;DR: The two-layered time-division structure of receiver activation and group TDMA algorithms offers distributed and polynomial-time solutions to the problems of link scheduling as well as energy and throughput-efficient resource allocation in wireless access.
Abstract: In this article we revisit the problem of scheduled access through a detailed foray into the questions of energy consumption and throughput for MAC protocols in wireless sensor networks. We consider a static network model that rules out simultaneous transmission and reception by any sensor node and consequently requires partitioning of nodes into disjoint sets of transmitters and receivers at any time instant. Under the assumption of circular transmission (reception) ranges with sharp boundaries, a greedy receiver activation heuristic is developed relying on the network connectivity map to determine distinct receiver groups to be activated within disjoint time intervals. To conserve limited energy resources in sensor networks, the time allocation to each receiver group is based on the residual battery energy available at the respective transmitters. Upon activating each receiver group separately, the additional time-division mechanism of group TDMA is imposed to schedule transmissions interfering at the non-intended destinations within separate fractions of time in order to preserve the reliable feedback information. The two-layered time-division structure of receiver activation and group TDMA algorithms offers distributed and polynomial-time solutions (as required by autonomous sensor networks) to the problems of link scheduling as well as energy and throughput-efficient resource allocation in wireless access. The associated synchronization and overhead issues are not considered in this article.


Journal ArticleDOI
TL;DR: A link-layer-assisted mobile IP handoff mechanism is introduced to improve the network/domain switching quality in terms of handoff delay and packet loss and an application layer end-to-end authentication and key negotiation scheme is proposed to overcome the open-air connection problem existing in wireless LAN deployment.
Abstract: A wireless LAN service integration architecture based on current wireless LAN hot spots is proposed so that migration to a new service becomes easier and cost effective. The proposed architecture offers wireless LAN seamless roaming in wireless LAN/cellular mobile networks. In addition, a link-layer-assisted mobile IP handoff mechanism is introduced to improve the network/domain switching quality in terms of handoff delay and packet loss. An application layer end-to-end authentication and key negotiation scheme is proposed to overcome the open-air connection problem existing in wireless LAN deployment. The scheme provides a general solution for Internet applications running on a mobile station under various authentication scenarios and keeps the communications private to other wireless LAN users and foreign network. A functional demonstration of the scheme is given. The research results can contribute to rapid deployment of wireless LANs.

Journal ArticleDOI
TL;DR: Possible architectures that enable the interworking of 3G and WLAN networks are presented and the capabilities of various terminal types are addressed, as well as market forecasts on terminal and service demand growth.
Abstract: Interworking WLANs and 3G mobile networks are expected to provide ubiquitous wireless communications at high data rates and a large variety of services with variable bandwidth and QoS requirements, across a wide range of propagation environments and mobility conditions, using dual mode terminals. The interworking of the two networks is a major step toward a new generation of wireless networks in which other radio technologies are also be integrated. In this article we present possible architectures that enable the interworking of 3G and WLAN networks. We then address the capabilities of various terminal types and describe future services in the interworking environment. Finally, we present market forecasts on terminal and service demand growth.

Journal ArticleDOI
TL;DR: Results from work carried out over the last few years at NTUA are presented, bringing us closer to the definition of such a flexible framework for cfficient management of content, which will be able to support the development of advanced telecommunications services and integrated real-time information provision and processing systems.
Abstract: Various types of sophisticated networks and terminals are used for the provision of thirdgeneration services, and even more complicated ones are designed for 4G systems. Roaming users will rely on new kinds of wireless networks and terminals to offer mobility and make multimedia services available everywhere. They will, of course, expect continuous access to personalized services from any place, transparently and independent of the underlying network technology and the terminal or point of access. Virtual home environment features were specified and implemented in order to satisfy these requirements in 3G systems. The enhanced role of IP in 4G systems and the assimilation of WLAN technology will enable further advances toward pervasive computing and the pursuit of corn-, plete context awareness in state-of-the-art applications and services. 4G services can he smarter and more adaptive by taking advantage of all types of context available to them within a well defined context management framework. This article presents results from work carried out over the last few years at NTUA,’ bringing us closer to the definition of such a flexible framework for cfficient management of content, which will he able to support the development of advanced telecommunications services and integrated real-time information provision and processing systems.

Journal ArticleDOI
TL;DR: A new model for service and application integration in 4G networks is presented, based on a hierarchical architecture that provides compatibility for services in different technologies and at the same time is able to capture the specific details for each particular technology.
Abstract: 4G mobile communication networks encompass heterogeneous technologies that can be categorized at different levels according to their access coverage. Personal area, body area, and ad hoc networks are defined at a personal level, WLAN and UWB are examples at a local/ home level, and 3G technologies such as UMTS are technologies at a cellular level. In spite of their heterogeneity, these technologies shall be seamlessly integrated in 4G networks, naturally creating an open architecture. By openness we mean that the network architecture is divided into different layers, and the communication between these layers is performed through open interfaces or APIs. Although this open integration between 4G technologies is normally presented at the lower layers (connectivity and control), integration at the upper layers (service and application) is equally important. In this article we present a new model for service and application integration in 4G networks. This model generalizes the different service and application creation environments defined for each of the previously mentioned technologies, providing a uniform and interoperable framework for 4G services and applications. The model is based on a hierarchical architecture that provides compatibility for services in different technologies and at the same time is able to capture the specific details for each particular technology. The model also defines how 4G applications should be specified. In the last part of this article we present a testbed we have implemented in order to validate this model.

Journal ArticleDOI
TL;DR: Simulation results demonstrate how an information-theory-motivated resource provisioning strategy can meet QoS bounds with very small wastage of resources, thus dramatically reducing the overall blocking rate.
Abstract: We utilize tools from information theory to develop adaptive algorithms for two key problems in cellular networks: location tracking and resource management. The use of information theory is motivated by the fundamental observation that overheads in many aspects of mobile computing can be traced to the randomness or uncertainty in an individual user's movement behavior. We present a model-independent information-theoretic approach for estimating and managing this uncertainty, and relate it to the entropy or information content of the user's movement process. Information-theoretic mobility management algorithms are very simple, yet reduce overhead by /spl sim/80 percent in simulated scenarios by optimally adapting to each individual's movement. These algorithms also allow for flexible tradeoff between location update and paging costs. Simulation results demonstrate how an information-theory-motivated resource provisioning strategy can meet QoS bounds with very small wastage of resources, thus dramatically reducing the overall blocking rate.