Handover management in integrated WLAN and mobile WiMAX networks [recent advances and evolution of WLAN and WMAN standards]

Recently there has been much effort, in both academia and industry, to integrate a plethora of wireless technologies in order to provide ubiquitous broadband access to mobile users. Handover management is still one of the most challenging issues to be solved for seamless integration of wireless networks. This article addresses the integration of IEEE 802.11 WLANs and IEEE 802.16 WMANs, focusing mainly on the handover management aspects. First, we describe architectures, futuristic application scenarios such as the envisioned heterogeneous multihop wireless networks (HMWNs) and moving networks, as well as the related research issues. Second, we present IEEE 802.21, a new emerging standard aimed at providing a framework for media-independent handover (MIH) among heterogeneous networks. Finally, we discuss how the MIH framework can help handover management for the integrated network.     

Variable bit rate VOiP in IEEE 802.11e wireless LANs [medium access control protocols for wireless LANs]

WLANs have become a ubiquitous networking technology deployed everywhere. Meanwhile. VoIP is one popular application and a viable alternative to traditional telephony systems due to its cost efficiency. VoIP over WLAN (VoWLAN) has been emerging as an infrastructure to provide low-cost wireless voice services. However, VoWLAN poses significant challenges due to the characteristics of contention-based protocols and wireless networks. In this article we propose two mechanisms to provide quality of service for variable bit rate VoIP in IEEE 802.11e contention-based channel access WLANs: access time-based admission control and access point dynamic access. Simulation results are conducted to study these schemes.     

Efficient Radio Resource Management in Integrated WLAN/CDMA Mobile Networks

The complementary characteristics of wireless local area networks (WLANs) and wideband code division multiple access (CDMA) cellular networks make it attractive to integrate these two technologies. How to utilize the overall radio resources optimally in this heterogeneous integrated environment is a challenging issue. This paper proposes an optimal joint session admission control scheme for multimedia traffic that maximizes overall network revenue with quality of service (QoS) constraints over both WLANs and CDMA cellular networks. WLANs operate under IEEE 802.11e medium access control (MAC) protocol, which supports QoS for multimedia traffic. A cross-layer optimization approach is used in CDMA networks taking into account both physical layer linear minimum mean square error (LMMSE) receivers and network layer QoS requirements. Numerical examples illustrate that the network revenue earned in the proposed joint admission control scheme is significantly more than that when the individual networks are optimized independently.     

The personnel distributed environment

Beyond 3G continues to dominate discussion within the cellular community. A variety of issues are being actively debated: the requirement for a new air interface, greater interworking with WLANs and other networks, a service-driven approach, and potential for increasing market penetration of network-enabled devices. The Mobile VCE vision for beyond 3G encompasses a world that has embraced a disparate range of networked processing and communications devices. This article presents an architecture for user-centric communication across heterogeneous access networks     

Toward Efficient Service-Level QoS Provisioning in Large-Scale 802.11-Based Networks

Along with recent advances in mobile networking and portable computing technologies, there is a trend in the telecommunications industry toward the development of efficient ubiquitous systems that can provide a set of bandwidth-intensive and real-time services to multiple users while supporting their full mobility. Large-scale deployment of 802.1 1-based technologies will play an integral part in the construction of such ubiquitous wireless mobile systems. A challenging task in the development of such networks is efficient provisioning of QoS-enabled services for mobile users. In this context, we propose a scheme that constantly monitors the overall network performance to perform admission control and traffic conditioning at the 802.11-based access points and mobile terminals. The focus is on service-level fairness, where different flows from the same traffic class can still receive the same QoS level even if they have different bit rates. Furthermore, given the mobility of users, the success of any resource allocation and admission control model depends on the continuity of QoS guarantees across different WLANs. This article proposes a dynamic service level agreement negotiation protocol that allows mobile terminals to perform handoffs between different WLANs while maintaining the agreed level or service. End users also can change their service levels in response to changes in network conditions.     

Space-time codes for future WLANs: principles, practice, and performance

The mobility and ubiquitous access afforded by wireless local area networks (WLANs) and high-performance portable products promise to revolutionize the way we live, work, and play. However, sustained improvements in the throughput of WLANs, while also supporting robust long-range operation, requires the use of multiple antennas at both the mobile terminal and the access point. This article reviews the various space-time coding and decoding technologies employed for capitalizing on the increased capacity of the multiple-input multiple-output (MIMO) radio channel. Also described is a channel sounding campaign performed in the office environments used to scope the expected performance of these space-time codes in realistic deployments.     

Dependability issues with ubiquitous wireless access [guest editorial]

Recent years have witnessed a proliferation of the number of wireless technologies available to access the Internet, ranging from wireless local area networks to cellular and broadcast systems, and ad hoc and mesh networks. While the emergence of these new technologies can enable truly ubiquitous Internet access, it also raises issues with the dependability of the Internet service delivered to users. Dependability in this context refers to the ability of a wireless access system to deliver specified services on which users can rely.     

Self‐adaptive routing protocols for integrating cellular networks,WLANs, and MANETs

A growing need to have ubiquitous connectivity has motivated our research to provide continuous connection between various wireless platforms such as cellular networks, wireless local area networks (WLANs), and mobile ad hoc networks (MANETs). In this paper, we consider integration at the routing layer and propose two adaptable routing protocols (IRP‐RD and IRP‐PD) that exploit topology information stored at the fixed network components (cellular base stations and WLAN access points) for the route discovery and maintenance processes. Our proposed protocols can provide connectivity to the cellular network and/or WLAN hotspots through multihop routing, while differ in the gateway discovery approach used. In IRP‐RD, multihop routes to gateways to the cellular network or WLAN hot spots are discovered on demand, while in IRP‐PD out of coverage users proactively maintain routes to the gateways. Furthermore, proposed protocols can be used in any heterogeneous scenario, combining a cellular network and WLANs operating in infrastructure or ad hoc (MANET) mode. We provide simulation results that demonstrate the effectiveness of the proposed integrated routing protocols and show the advantages and drawbacks of each gateway discovery approach in different heterogeneous scenarios. Copyright © 2006 John Wiley & Sons, Ltd.     

Key Technologies of Wireless Heterogeneous Network Security

Convergence and collaboration of heterogeneous networks in the next generation public mobile networks will be a subject of universal significance. Convergence of heterogeneous networks, as an effective approach to improve the coverage and capacity of public mobile network, to enable communication services, to provide Internet access and to enable mobile computing from everywhere, has drawn widespread attention for its good prospects in application. Construction of security system for wireless heterogeneous networks and development of new security models, key security techniques and approaches are critical and mandatory in heterogeneous networks development. Key technology of wireless heterogeneous networks security covers security routing protocol, access authentication, intrusion detection system, cooperative communication between nodes, etc.     

A study on the channel bonding in IoT networks: Requirements,applications, and challenges

The most well-known sort of remote Internet connection is wireless local area networks (WLANs) due to its unsophisticated operation and deployment. Subsequently, the quantity of gadgets getting to the Internet through WLANs, for example, PCs, cell phones, or wearables, is expanding radically at the equivalent time that applications' throughput necessities do. To provide wireless networks with supplementary spectral resources, the researchers are considering the aggregation of frequency spectrums in licensed, unlicensed, and shared access (SA) bands. Channel aggregation/channel bonding (CA/CB) techniques accumulate quite a few channels together as one channel for the purpose of achieving better bandwidth utilization. In this study, we focus on reliable CA/CB techniques in different wireless networks. CA/CB procedures are utilized for empowering higher information rates by transmitting in more extensive channels, accordingly expanding range proficiency with the assured secure channel for communication. We also discuss the spectral scarcity issues in today's wireless IoT network. This paper presents an extensive survey on CA/CB procedures and methods, issues and challenges, and open research areas related to IoT devices. We analyze the performance of channel CA/CB strategies in the different wireless networks too.     

A hierarchical radio resource management framework for integrating WLANs in cellular networking environments

Over the last few years wireless local area networking (WLAN) has become a very important technology that offers high-speed communication services to mobile users in indoor environments. WLAN technology offers some very attractive characteristics such as high data rates, increased QoS capabilities, and low installation costs which has made many professionals claim that it will be the main opponent of IMT-2000, despite the enormous effort needed for the specification and implementation of 3G systems. However, WLANs also present many important constraints related mainly to their restricted coverage capabilities. On the other hand, 3G systems are deployed gradually and carefully since their business prospects have not been validated yet and it is expected that 2G and 2G+ cellular systems will continue to play an important role for at least five more years. Thus, today's wireless networking environment is in fact a conglomeration of all these technologies for which there is a strong need for cooperation. In this article we describe a heterogeneous wireless networking environment together with its features and user requirements. We explain the importance of the existence of WLANs and describe a framework and system architecture that supports seamless integration of WLAN in heterogeneous cellular networking environments, focusing on support for efficient resource provision and management.     

Architecture and enablers for optimized radio resource usage in heterogeneous wireless access networks: The IEEE 1900.4 Working Group

Over the past decade or so, the wireless industry has undergone many significant changes. Radio systems have moved toward forming heterogeneous wireless networks: collaborations of multiple radio access networks, which in some cases operate different radio access technologies, such as second- and third-generation cellular RATs, IEEE 802.x wireless standards, and so on. On the other hand, multimode reconfigurable user devices with the ability to choose among various supported RATs have become a reality, and devices and networks with dynamic spectrum access capabilities, allowing real-time sharing of spectrum resource usage among different systems, are expected to be a part of the future radio eco-space. As a result of these changes, there is a need to develop a standard that addresses the requirements and leverages the opportunities posed by such a versatile radio environment. To this end, IEEE 1900.4 aims to standardize the overall system architecture and information exchange between the network and mobile devices, which will allow these elements to optimally choose from available radio resources. In other words, the standard facilitates the distributed dynamic optimization of the usage of spectrum offered by the heterogeneous wireless network, relying on a collaborative information exchange between networks and mobile devices, thereby acting as a common means to improve overall composite capacity and quality of service for the served networks. This article provides a snapshot of IEEE P1900.4 in its current form, covering the scope and purpose of the standard, reference use cases for which the standard is applicable, its system and functional architectures, and finally, the information model for its main interfaces.     

Wireless technologies for telemedicine

Wireless telemedicine is a new and evolving area in telemedical and telecare systems. Healthcare personnel require realtime access to accurate patient data, including clinical histories, treatments, medication, tests, laboratory results and insurance information. With large-scale wireless networks and mobile computing solutions, such as cellular 3G, Wi-Fi mesh and WiMAX, healthcare personnal can tap into vital information anywhere and at any time within the healthcare networks. The recent introduction of pervasive computing, consisting of radio frequency identification (RFID), Bluetooth, ZigBee, and wireless sensor networks, further extends the potential for exploitation of wireless telecommunications and its integration into new mobile healthcare delivery systems. In this paper, snapshots of current uses and future trends of various wireless communications in the healthcare domain are highlighted. Special attention is given to the challenges of a telemedicine environment equipped with different wireless technologies and how the resulting issues might be addressed in medical services integration to provide flexible, convenient and economical medical monitoring, consultation and healthcare.     

Realizing the Ubiquitous Network: the Internet and Beyond

Two major properties will characterize networks in the future: ‘3C everywhere’ and ‘physical interaction’. These two properties promise a computing infrastructure that seamlessly and ubiquitously aids users in accomplishing their tasks and that renders the actual computing devices and technology largely invisible. This paper begins by providing a brief overview of the emerging technologies that may influence the new ubiquitous network (UbiNet) architecture. The following section presents our STONE (Service Synthesizer on the Net) project at the University of Tokyo. We designed STONE to provide distributed transparency, service consistency, and context-awareness, and explored communication and computation technologies in a sensor-instrumented environment.     

Interworking Architectures for IP Multimedia Subsystems

The future fourth generation wireless heterogeneous networks aim to integrate various wireless access technologies and to support the IMS (IP multimedia subsystem) sessions. In this paper, we propose the Loosely Coupled Satellite-Cellular-WiMAX-WLAN (LCSCW2) and the Tightly Coupled Satellite- Cellular-WiMAX-WLAN (TCSCW2) interworking architectures. The LCSCW2 and TCSCW2 architectures use the loosely coupling and tightly coupling approach, respectively. Both of them integrate the satellite networks, third generation (3G) wireless networks, worldwide interoperability for microwave access (WiMAX), and wireless local area networks (WLANs). They can support IMS sessions and provide global coverage. The LCSCW2 architecture facilitates independent deployment and traffic engineering of various access networks. The TCSCW2 architecture can provide quality of service (QoS) guarantee. We also propose an analytical model to determine the associate cost for the signaling and data traffic for inter-system communication in these architectures. The cost analysis includes the transmission, processing, and queueing costs at various entities. Numerical results are presented for different arrival rates and session lengths.     

A survey of mobility management in next-generation all-IP-based wireless systems

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.     

Opportunities and challenges in using WPAN and WLAN technologies in medical environments [Accepted from Open Call]

The present view of medical environments, where isolated networks are used for IT and medical applications, is changing toward an integrated heterogeneous network scenario that can support a wide range of applications. WPAN and WLAN technologies play a fundamental role in enabling such integrated environment that is expected to support both medical and nonmedical applications. The ultimate goal is to exploit WPAN and WLAN technologies, as well as other wireless networks, such as 3G cellular systems and satellite networks, to support highly efficient medical care delivery, anytime and anywhere. However, the life-critical nature of some medical applications imposes additional challenges that have not been considered in nonmedical scenarios. This article discusses some future scenarios where WLAN and WPAN technologies can be used to provide an integrated and ubiquitous network in medical environments, and identifies the main issues to be addressed in order to meet the QoS requirements of different medical applications when operating in integrated environment     

A call admission control framework for voice over WLANs

In this article a call admission control framework is presented for voice over wireless local area networks (WLANs). The framework, called WLAN voice manager, manages admission control for voice over IP (VoIP) calls with WLANs as the access networks. WLAN voice manager interacts with WLAN medium access control (MAC) layer protocols, soft-switches (VoIP call agents), routers, and other network devices to perform end-to-end (ETE) quality of service (QoS) provisioning and control for VoIP calls originated from WLANs. By implementing the proposed WLAN voice manager in the WLAN access network, a two-level ETE VoIP QoS control mechanism can be achieved: level 1 QoS for voice traffic over WLAN medium access and level 2 QoS for ETE VoIP services in the networks with WLANs as the local access. The implementation challenges of this framework are discussed for both level 1 and level 2. Possible solutions to the implementation issues are proposed and other remaining open issues are also addressed.     

On architectures for broadband wireless systems

The growing popularity of portable and mobile computing and communication devices, along with the introduction of wireline broadband networks, is fueling demand for wireless broadband networks. Since ATM has been accepted as the standard for broadband integrated service networks, the authors consider the problem of providing “ATM-like services” to mobile devices. The fundamental issues that have to be tackled in order to provide broadband services which are currently available (or will be very shortly) to wireline hosts are discussed. The authors compare and contrast the architectures that have been proposed for extending the broadband wireline network infrastructure to the wireless environment. It is argued that transporting small ATM cells over the air leads to inefficient utilization of the already scarce transmission capacity. Subsequently, the authors propose an architecture for integrated wireless and wireline broadband networks which allows the wireline and wireless parts of the network to be designed independently, therefore allowing each to be optimized for the environment in which it operates. At the same time, the proposed architecture also permits simple and efficient interconnection between the wireline and wireless infrastructures     

A Virtual MAC Address Scheme for Mobile Ethernet

Heterogeneous wireless access is being integrated into IP networks to support future wireless systems. The enhanced IP technologies being developed must address both handover issues related to mobility management and security issues related to wireless access. We previously proposed a network architecture, Mobile Ethernet, based on wide area Ethernet technologies, that reduces overhead involving handover by managing mobility in the IEEE802 MAC layer. We also proposed a virtual MAC address scheme that introduces a host identifier into layer 2 to accommodate heterogeneous wireless access, manage handover between wireless accesses, provide scalability, and ensure security. In this paper, we design the virtual MAC address scheme for Mobile Ethernet and describe the sequence diagrams of the scheme. We also clarify the effect of our proposed scheme from the viewpoint of scalability by comparing the simulated signaling traffic load at handover with that using FMIPv6. Yoshia Saito received his B.E. and M.E. degrees from Shizuoka University, Shizuoka, Japan, in 2002 and 2003 respectively. He is currently a student in Ph.D. course in the university. From January 2004, he is also working as a visiting researcher at National Institute of Information and Communications Technology, Yokosuka, Japan. His research interests include mobile computing and next generation wireless systems. Masahiro Kuroda received the M.E. degree in systems science from the Tokyo Institute of Technology, Japan, in 1980, the M.S. degree in computer science from University of California, Santa Barbara, CA, in 1989, and received the Ph.D. degree in computer science from Shizuoka University, Japan, in 2000. He joined Mitsubishi Electric Corporation, Kamakura, Japan in 1980. Since then, he was engaged in OS/network developments, mobile network computing R&D, and cellular Java standardizations. He is currently working as a group leader at National Institute of Information and Communications Technology, Yokosuka, Japan. His current research interests includes wireless network, wireless security, mobile systems, ubiquitous systems, and next generation wireless systems architecture. He is a member of the IEEE Computer Society. Tadanori Mizuno received the B.E. degree in industrial engineering from the Nagoya Institute of Technology in 1968 and received the Ph.D. degree in computer science from Kyushu University, Japan, in 1987. In 1968, he joined Mitsubishi Electric Corp. Since 1993, he is a Professor of Faculty of Engineering, Shizuoka University, Japan. He moved to the Faculty of Information, Shizuoka University in 1995. His research interests include mobile computing, distributed computing, computer networks, broadcast communication and computing, and protocol engineering. He is a member of Information Processing Society of Japan, the institute of electronics, information and Communication Engineers, the IEEE Computer Society and ACM.