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Wireless Communications, IEEE

Issue 6 • Date Dec. 2002

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Displaying Results 1 - 14 of 14
  • Guest Editorial - Wireless LANs

    Page(s): 6 - 7
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    Freely Available from IEEE
  • Guest Editorial - Smart Homes

    Page(s): 62
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    Freely Available from IEEE
  • Reduced dimension space-time processing for multi-antenna wireless systems

    Page(s): 18 - 25
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (739 KB) |  | HTML iconHTML  

    The need for wireless communication systems has grown rapidly during the last few years. Moreover, there is a steady growth in the required data rates due to the fact that more and more users request high-bit-rate services. To meet those requirements, current and next-generation wireless systems and networks such as wireless LANs (e.g., IEEE 802.11a) will support much higher data rates compared with established standards. This is basically done by applying advanced transmission schemes and usage of bandwidth resources. Another very promising approach is the introduction of multiple antennas at one or both ends of a link to exploit the spatial dimension of signal transmission for improved link quality and enhanced system capacity. Smart antenna concepts are extensively discussed in this context. The application of concepts with multiple antennas necessitates the introduction of more advanced and computational expensive transmitter and receiver structures, where space-time (ST) processing techniques are required to carry out spatial and temporal information processing jointly. This article introduces a new ST processing concept to enable reduced dimension ST receiver signal processing. The signal dimension can be considerably reduced compared to the number of antennas by exploiting spatial correlation properties of the received antenna signals. The associated signal transformation applies the concept of the Karhunen-Loeve transformation (KLT). A great advantage of the proposed ST processing concept over traditional multiple antenna approaches is the insensitivity of the algorithms to the antenna characteristics and antenna spacing, which allows the use of low-cost antennas. Another significant advantage of the proposed concept is more robust channel estimation due to spatial dimension reduction and the resulting limitation of estimation parameters. View full abstract»

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  • Your 80211 wireless network has no clothes

    Page(s): 44 - 51
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    The explosive growth in wireless networks over the last few years resembles the rapid growth of the Internet within the last decade. To protect internal resources, organizations usually purchased and installed an Internet firewall. We believe that the currently deployed wireless access points present a larger security problem than the early Internet connections. A large number of organizations, based on vendor literature, believe that the security provided by their deployed wireless access points is sufficient to prevent unauthorized access and use. Unfortunately, nothing could be further from the truth. While the current access points provide several security mechanisms, our work combined with the work of others show that all of these mechanisms are completely ineffective. As a result, organizations with deployed wireless networks are vulnerable to unauthorized use of, and access to, their internal infrastructure. We present a novel solution that requires no changes or additions to any deployed wireless equipment, and is easily deployed and transparent to end users. View full abstract»

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  • Adequacy between multimedia application requirements and wireless protocols features

    Page(s): 26 - 34
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    Wireless networks come in force into the market of computer communications. Unfortunately, several standards coexist (e.g., IEEE 802.11, Bluetooth, HomeRF, HIPERLAN), leading to various types of products. The purpose of this article is to present an overview of those standards and to establish a comparative evaluation. We mainly focus on the medium access control protocols and their ability to support the quality of service required by multimedia applications. Those protocols generally support two modes of operation, a random access mode for asynchronous traffic and a polling mode for real-time synchronous traffic. This article analyzes each protocol's ability to support user QoS requirements. View full abstract»

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  • A hybrid analysis and architectural design method for development of smart home components

    Page(s): 85 - 91
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    Accurate requirements provide the foundation for successful product development. Determining accurate requirements is difficult in many cases and is especially problematic in new and rapidly evolving domains. Development of smart home technologies provides such a challenge due to their dynamic design environment consisting of emergent technology, with minimal existing systems to evaluate, few standards, and users with vague ideas of the benefits or the possibilities. The most troubling problem, however, is how to optimize user satisfaction considering the wide range of user types and preferences and the dynamic system environment created by constant introduction of new products. For early development in this user-focused environment, we propose a new approach based on the synthesis of well established techniques from software engineering, management theory, and hardware product development. We propose the fusion of the use case and house of quality analysis models, simulators, and prototypes, and information processing theory coordination techniques. View full abstract»

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  • Stanford interactive workspaces: a framework for physical and graphical user interface prototyping

    Page(s): 64 - 69
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    Most smart homes are created evolutionarily by adding more and more technologies to an existing home, rather than being developed on a single occasion by building a new home from scratch. This incremental addition of technology requires a highly flexible infrastructure to accommodate both future extensions and legacy systems without requiring extensive rewiring of hardware or extensive reconfiguration on the software level. Stanford's iStuff (Interactive Stuff) provides an example of a hardware interface abstraction technique that enables quick customization and reconfiguration of Smart Home solutions. iStuff gains its power from its combination with the Stanford Interactive Room Operating System (iROS), which creates a flexible and robust software framework that allows custom and legacy applications to communicate with each other and with user interface devices in a dynamically configurable way. The Stanford Interactive Room (iRoom), while not a residential environment, has many characteristics of a smart home: a wide array of advanced user interface technologies, abundant computation power, and infrastructure with which to coordinate the use of these resources (for more information on the iRoom or the Interactive Workspaces project, please visit http://iwork.stanford.edu). As a result, many aspects of the iRoom environment have strong implications for, and can be intuitively translated to, smart homes. In particular, the rapid and fluid development of physical user interfaces using iStuff and the iROS, which has been demonstrated in the iRoom, is an equally powerful concept for designing and living in smart homes. Before focusing on the details of iStuff, we describe the software infrastructure on which it is based and the considerations that went into designing this infrastructure. View full abstract»

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  • Co-channel interference cancellation based on MIMO OFDM systems

    Page(s): 8 - 17
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    This article deals with the exploitation of multiple input multiple output (MIMO) systems for broadband wireless indoor applications. Two systems, the Wind-Flex and ubiquitous antenna, are considered. Both aim to increase the system capacity by different approaches, to increase the single link data rate and the number of users in the whole system, respectively. Computer simulation results show the effectiveness of both MIMO systems. View full abstract»

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  • Vertical optimization of data transmission for mobile wireless terminals

    Page(s): 36 - 43
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    A major problem for TCP connections over wireless links is that errors introduced by the wireless channel interfere with the TCP protocol, leading to reduced data rates and power wastage. Based on accurate simulations for the TCP and IEEE 802.11 MAC protocols, we discuss recipes to optimize transmission. It is argued that the best approach is to restrict modifications to the mobile device. While this requires separate solutions for the uplink and downlink, the results of optimization are then available when roaming into any WLAN obeying the relevant MAC protocol. Simulation results show that the combination of specific strategies with a vertical interaction between the protocol layers can lead to the required improvements, giving a promising approach to enhance the performance of wireless mobile terminals. View full abstract»

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  • The role of prediction algorithms in the MavHome smart home architecture

    Page(s): 77 - 84
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (698 KB) |  | HTML iconHTML  

    The goal of the MavHome project is to create a home that acts as a rational agent. The agent seeks to maximize inhabitant comfort and minimize operation cost. To achieve these goals, the agent must be able to predict the mobility patterns and device usages of the inhabitants. We introduce the MavHome project and its underlying architecture. The role of prediction algorithms within the architecture is discussed, and three prediction algorithms that are central to home operations are presented. We demonstrate the effectiveness of these algorithms on synthetic and/or actual smart home data. View full abstract»

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  • A power line communication network infrastructure for the smart home

    Page(s): 104 - 111
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    Low voltage electrical wiring has largely been dismissed as too noisy and unpredictable to support high-speed communication signals. Advances in communication and modulation methodologies as well as in adaptive digital signal processing and error detection and correction have spawned novel protocols capable of supporting power line communication networks at speeds comparable to wired LANs. We motivate the use of power line LANs as a basic infrastructure for building integrated smart homes, wherein information appliances ranging from simple control or monitoring devices to multimedia entertainment systems are seamlessly interconnected by the very wires that provide them electricity. By simulation and actual measurements using "reference design" prototype commercial powerline products, we show that the HomePlug MAC and PHY layers can guarantee QoS for real-time communications, supporting delay-sensitive data streams for smart home applications. View full abstract»

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  • Cellular access control and charging for mobile operator wireless local area networks

    Page(s): 52 - 60
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    This article presents a system architecture, design considerations, and rationale for a mobile operator wireless LAN. The article also discusses the system implementation and performance issues. The system presented reuses GSM and GPRS mechanisms for user authentication, access control, subscriber management, operator roaming, and billing, while still being compatible with wireless Internet service provider networks and IETF and IEEE protocols such as RADIUS, EAP, and IEEE 802.1x. The architecture is a result of research carried out by Nokia between 1999 and 2002. The designed architecture has also been verified in a complete system implementation. View full abstract»

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  • Facilitating the programming of the smart home

    Page(s): 70 - 76
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    The ongoing miniaturization and cost reduction in electronic hardware has created opportunity for equipping homes with inexpensive smart devices for controlling and automating various tasks in our daily lives. Networking technology and standards have an important role in driving this development. We discuss how technological progress in the areas of visual programming languages, component software, and connection-based programming can be applied to programming the smart home. As an example of an industrial prototype solution, we present microCommander, a visual tool for rapidly programming synergetic devices for the smart home. View full abstract»

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  • An adaptive sniff scheduling scheme for power saving in Bluetooth

    Page(s): 92 - 103
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (865 KB) |  | HTML iconHTML  

    Bluetooth is expected to be an important basic constructing component for smart homes. In a smart home environment, many devices will be portable and battery-operated, making power saving an essential issue. The authors study the problem of managing the low-power sniff mode in Bluetooth, where a slave is allowed to be awake only periodically. One challenging problem is how to schedule each slave's sniffing period in a piconet so as to resolve the trade-off between traffic and power-saving requirements, to which we refer as the sniff-scheduling problem. We propose an adaptive protocol to dynamically adjust each slave's sniff parameters, with a goal of catching the varying, and even asymmetric, traffic patterns among the master and slaves. Compared to existing works, our work is unique. First, our scheduling considers multiple slaves simultaneously. Existing work only considers one slave, and different slaves are treated independently. Second, our scheduling is more accurate and dynamic in determining the sniff-related parameters based on slaves' traffic patterns. Most work is restricted to a naive exponential adjustment in sniff interval/sniff-attempt window. Third, our proposal includes the placement of sniff-attempt periods of sniffed slaves on the time axis when multiple slaves are involved. This issue is ignored by earlier work. Extensive simulation results are presented. View full abstract»

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Aims & Scope

IEEE Wireless Communications Magazine deals with all technical and policy issues related to personalization, location-independent communications in all media.

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Meet Our Editors

Editor-in-Chief
Hsiao-Hwa Chen
Cheng Kung University, Taiwan