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Wireless Communications, IEEE

Issue 6 • Date December 2011

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Displaying Results 1 - 15 of 15
  • IEEE Wireless Communications - Front cover

    Page(s): c1
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    Freely Available from IEEE
  • Table of contents

    Page(s): 1
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  • Spectrum efficiency, energy saving, and security are still foundational issues to tackle [Message from the Editor-in-Chief]

    Page(s): 2 - 3
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  • Antenna design challenges for 4G

    Page(s): 4 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (266 KB) |  | HTML iconHTML  

    The trend in mobile wireless devices has been to provide faster access, improved processors, more memory, brighter and higher resolution screens, additional connectivity with Wi-Fi, GPS, third generation (3G), and fourth generation (4G) world access - all with longer battery life in thinner, sleeker packages. Compound this with the desire of mobile operators to expand their available band allocations, and what results is a difficult industrial design arena, where suppliers are vying afor physical space within the confines of a smartphone or similar device to accommodate necessary components. View full abstract»

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  • WiGiG: Multi-gigabit wireless communications in the 60 GHz band

    Page(s): 6 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (191 KB) |  | HTML iconHTML  

    The Wireless Gigabit Alliance [1] - commonly called WiGig - is an industry consortium devoted to the development and promotion of wireless communications in the 60 GHz band. Recent advances in 60 GHz technology and demand for higher-speed wireless connections are key drivers for WiGig. Among the unlicensed frequency bands available for wireless networks, 60 GHz is uniquely suited for carrying extremely high data rates (multiple gigabits per second) over short distances. WiGig has developed a medium access control (MAC) layer, a physical (PHY) layer, and several protocol adaptation layers (PALs) to enable interoperable devices that take advantage of these extremely high data rates. WiGig is also working closely with standards bodies, including IEEE 802.11, and other industry groups, such as the Wi-Fi Alliance, to help enable certification of standards-compliant devices. View full abstract»

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  • Scanning the literature

    Page(s): 8 - 9
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  • Which DTN CLP is best for long-delay cislunar communications with channel-rate asymmetry?

    Page(s): 10 - 16
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (210 KB) |  | HTML iconHTML  

    Delay-/disruption-tolerant networking is considered one of the most suitable technologies to handle the delays and disconnection inherent in space internetworking. To date, little work has been done in evaluating its effectiveness in cislunar communications involving long link delay and highly asymmetric channel rates. In this article, we present an experimental study of DTN convergence layer protocols over a typical cislunar communication infrastructure accompanied by a very long link delay, various asymmetric channel rates, and varying data loss rate. The intent of the work was to find answers to two questions: which CLP is the best for long-delay cislunar communications in the presence of highly asymmetric channel rates, and whether aggregation of bundle protocol bundles is helpful for improving goodput of DTN in the presence of IPN channel asymmetry. View full abstract»

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  • A queueing-theoretical framework for QoS-enhanced spectrum management in cognitive radio networks

    Page(s): 18 - 26
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (429 KB) |  | HTML iconHTML  

    This article outlines the fundamental modeling issues of opportunistic spectrum access in cognitive radio networks. In particular, we identify the effects of connection-based channel usage on the QoS performance of spectrum management techniques. During the transmission period of a secondary user's connection, the phenomenon of multiple spectrum handoffs due to interruptions of primary users arises quite often. In addition to multiple interruptions, the connection-based channel usage behaviors are also affected by spectrum sensing time, switching between different channels, generally distributed service time, and channel contention between multiple secondary users. An analytical framework based on the preemptive resumption priority M/G/1 queueing theory is introduced to characterize the effects of the above factors simultaneously. The proposed generalized analytical framework can incorporate various system parameters into the design of very broad spectrum management techniques, including spectrum sensing, spectrum decision, spectrum sharing, and spectrum mobility. The applications of this analytical framework on spectrum decision as well as spectrum mobility are discussed, and some open issues using this framework are suggested in this article. View full abstract»

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  • Energy-efficient wireless communications: tutorial, survey, and open issues

    Page(s): 28 - 35
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (355 KB) |  | HTML iconHTML  

    With explosive growth of high-data-rate applications, more and more energy is consumed in wireless networks to guarantee quality of service. Therefore, energy-efficient communications have been paid increasing attention under the background of limited energy resource and environmental- friendly transmission behaviors. In this article, basic concepts of energy-efficient communications are first introduced and then existing fundamental works and advanced techniques for energy efficiency are summarized, including information-theoretic analysis, OFDMA networks, MIMO techniques, relay transmission, and resource allocation for signaling. Some valuable topics in energy-efficient design are also identified for future research. View full abstract»

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  • Energy-efficient wireless in-home: the need for interference-controlled femtocells

    Page(s): 36 - 44
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2502 KB) |  | HTML iconHTML  

    Fostering growth in provisioning of wireless data at the same or even reduced energy expenditure levels, is crucial to society and thus one of the most important goals of the ICT sector. Femtocells, installed at customer premises, have emerged as a promising energy-efficient solution as connectivity is provided where and when needed. This article thus first overviews femtocell deployments in the context of 3G LTE and its advanced (LTE-A) networks. It is shown that to increase spectral efficiency, operators envisage utilizing the same spectrum for femtocells as well as overlaying macrocells. This in turn leads to significant interference between macro and femto as well as adjacent femtocells, the mitigation of which yields some major power gains. We therefore present various recent interference management schemes and quantify their throughput in the context of an LTE-A cellular network overlaying femtocells. Complete downlink system-level simulations corroborate exposed analysis and thus confirm the performance effectiveness of femtocell deployments. View full abstract»

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  • Wireless data center networking

    Page(s): 46 - 53
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (320 KB) |  | HTML iconHTML  

    Data centers play a key role in the expansion of cloud computing. However, the efficiency of data center networks is limited by oversubscription. The typical unbalanced traffic distributions of a DCN further aggravate the problem. Wireless networking, as a complementary technology to Ethernet, has the flexibility and capability to provide feasible approaches to handle the problem. In this article, we analyze the challenges of DCNs and articulate the motivations of employing wireless in DCNs. We also propose a hybrid Ethernet/wireless DCN architecture and a mechanism to dynamically schedule wireless transmissions based on traffic demands. Our simulation study demonstrates the effectiveness of the proposed wireless DCN. View full abstract»

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  • Cellular system physical layer throughput: How far off are we from the shannon bound?

    Page(s): 54 - 63
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (461 KB) |  | HTML iconHTML  

    Cellular wireless systems have made impressive progress over the past two decades. They currently connect more than five billion people worldwide. With the advent of turbo decoders in the 1990s, the design of optimal decoders very close to the Shannon bound became possible in AWGN channels. Nowadays many researchers believe that this is true for entire wireless systems and that therefore there is not much left to investigate. In this contribution, we take a closer look at WiMAX and HSDPA, two successful cellular systems being operated currently in many countries, and check their truly achievable performance. We have measured the physical layer throughput of WiMAX and HSDPA in various realistic environments (urban and mountainous) with high-quality equipment and different antenna configurations. We furthermore compared the throughput measured to the Shannon bound. Based on our measurements, we analyze the losses in design and implementation (e.g., pilots, guard carriers, coding, equalization, and channel estimation) and report our findings. Surprisingly, we are currently only utilizing 40 percent of the available channel capacity; or roughly equivalently, we are up to 10 dB off the Shannon bound at typical operational points, thus providing a lot of potential improvement for future 4G systems. In advanced four transmit antenna configurations of HSDPA, the losses are even more pronounced, showing that our current standards are not well suited to take advantage of the much higher capacity provided. View full abstract»

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  • LRPF: an RF coverage reporting protocol for LTE systems

    Page(s): 64 - 72
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1449 KB) |  | HTML iconHTML  

    For the 3GPP Long Term Evolution standard, the 3GPP have proposed a minimization of drive tests (MDT) feature to centrally collect RF environment measurements from end UE terminals and associate them with location coordinates. This article presents a novel implementation of the MDT feature, the LTE RF Performance Reporting Protocol (LRFP). LRFP utilizes RF measurements based on radio resource control protocol signaling, and location intelligence and transport of information based on the LTE Positioning Protocol Annex (LPPa), in addition to intelligent transport and storage mechanisms. In this article, we first provide a detailed overview of the proposed LRPF protocol. We then present our system simulation methodology and evaluate the impact of LRFP on the key requirements for MDT protocols, such as UE terminal power consumption and network signaling overhead, both of which show positive outcomes. View full abstract»

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  • Harmonized mobility management in IMS networks based on the SSON concept

    Page(s): 74 - 81
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (309 KB) |  | HTML iconHTML  

    As IP communications become abundant in the mobile world, the beyond 3G network concept tends to find anchorage in IMS technology. IMS shows potential for supporting rich-content applications and mixed user communication scenarios over mobile, wireless, and fixed access interfaces. IMS important advancement is the capacity for "liberalized" communications, where service provisioning is decoupled from the network infrastructure, thus making possible deployment across multi-operator networks. This article introduces such a federation mechanism for harmonized user mobility management, based on the Single Sign ON (SSON) concept of network registration. We demonstrate how the SSON functionality can be incorporated in the IMS architecture and exploited in achieving seamless user handover/ roaming and service continuity across multi-operator mixed-technology networks. View full abstract»

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  • Survivable key management on WANETs

    Page(s): 82 - 88
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (209 KB) |  | HTML iconHTML  

    Key management is an essential service for wireless ad hoc networks. It supports the secure operation of other network services like routing, end-to-end communication, and connectivity that rely on cryptography primitives to create security solutions. Designing key management systems for WANETs is a demanding task due to the self-organization of the network and the lack of a central entity controlling node participation in network services. Furthermore, key management operations should be continuously provided even if the network is partly compromised or experiences failures, attacks, or intrusions. This article gives an overview of existing key management systems for WANETs, highlighting their drawbacks related to survivability. Then it presents SG-PKM, a survivable public key infrastructure for WANETs. SG-PKM uses groups based on users' relationships to increase survivability in the presence of different types of attacks. Finally, it highlights open issues in designing survivable key management systems. 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