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Wireless Communications, IEEE

Issue 6 • Date December 2012

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Displaying Results 1 - 19 of 19
  • IEEE Wireless Communications - front cover

    Publication Year: 2012 , Page(s): c1
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  • Table of contents

    Publication Year: 2012 , 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]

    Publication Year: 2012 , Page(s): 2 - 4
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  • Spectrum sharing issues on both sides of the atlantic

    Publication Year: 2012 , Page(s): 6 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (47 KB) |  | HTML iconHTML  

    Possible increased sharing of spectrum is being considered on both sides of the Atlantic as spectrum needs increase rapidly with increased mobile use for broadband. In addition, the success of Wi-Fi and Bluetooth have resulted in a demand for unlicensed spectrum (also called ?????????license exempt????????? spectrum and ?????????collective use of spectrum????????? (CUS) in some countries) with a possibly lower availability than traditional licensed spectrum. In the past it was generally possible to meet evolving spectrum needs of various incumbent and prospective users by either dividing spectrum up into bands that were exclusive to one class of users or shared between users with special characteristics that facilitated sharing, or using more efficient modulation technology or system design to increase spectrum efficiency to meet demand. But now there is a vanishingly small amount of potential mobile spectrum in industrialized countries that is either idle or easily repurposed from existing uses. Thus there is growing interest in exploring spectrum sharing in a number of countries although those seeking new spectrum access generally would prefer a traditional exclusive allocation.ossible increased sharing of spectrum is being considered on both sides of the Atlantic as spectrum needs increase rapidly with increased mobile use for broadband. In addition, the success of Wi-Fi and Bluetooth have resulted in a demand for unlicensed spectrum (also called ?????????license exempt????????? spectrum and ?????????collective use of spectrum????????? (CUS) in some countries) with a possibly lower availability than traditional licensed spectrum. In the past it was generally possible to meet evolving spectrum needs of various incumbent and prospective users by either dividing spectrum up into bands that were exclusive to one class of users or shared between users with special characteristics that facilitated sharing, or using more efficient modulation technology or system design- to increase spectrum efficiency to meet demand. But now there is a vanishingly small amount of potential mobile spectrum in industrialized countries that is either idle or easily repurposed from existing uses. Thus there is growing interest in exploring spectrum sharing in a number of countries although those seeking new spectrum access generally would prefer a traditional exclusive allocation. View full abstract»

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  • Scanning the literature

    Publication Year: 2012 , Page(s): 8 - 9
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  • Enabling pervasive healthcare through continuous remote health monitoring

    Publication Year: 2012 , Page(s): 10 - 18
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (739 KB) |  | HTML iconHTML  

    In this article, we introduce a novel remote health monitoring (RHM) system to enable high-quality pervasive healthcare services to users with low delivery delay and reduced costs. We define the RHM architecture and summarize the design considerations. We then present a promising commercialized solution, ViiCare, with system infrastructures and supporting techniques. We also discuss future research challenges for implementing RHM systems. View full abstract»

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  • On combating the half-duplex constraint in modern cooperative networks: protocols and techniques

    Publication Year: 2012 , Page(s): 20 - 27
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (293 KB) |  | HTML iconHTML  

    A key issue that characterizes cooperative wireless networks is the half-duplex constraint (HDC), which refers to the inability of current modems to receive and transmit data in the same frequency at the same time. This hardware limitation results in inefficient use of system resources (bandwidth loss) as it requires dedicated bandwidth allocation for relay transmissions. Methods to overcome the HDC have been studied intensively in the literature of cooperative networks in recent years, and several approaches have been proposed. In this article we highlight four different techniques which combat the HDC by using existing technology. The first approach is non-orthogonal protocols, which allow the source to be active during relay transmissions. The second approach is the overlap of several relaying transmissions in order to mimic an ideal full-duplex operation. The third solution is the two-way relay channel where two sources exchange data via the assistance of a shared relay. Finally, the fourth approach incorporates cooperation on the "network" level and uses the cognitive radio concept to enable relay transmissions during silent periods of source terminals. These techniques summarize some of the most significant HDC solutions that cover both the physical and network layers. View full abstract»

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  • Personal satellite communication: technologies and challenges

    Publication Year: 2012 , Page(s): 28 - 35
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1132 KB) |  | HTML iconHTML  

    Communication regulatory bodies in many parts of the world have recently granted satellite operators the right to extend their networks by adding ground segments. This has opened the door, for the first time, to truly ubiquitous satellite coverage, thus revolutionizing the use of satellites in personal communications. In this article, we review personal satellite communication systems. Background on the evolution of satellite communications is given along with the basics of satellite systems. This is followed by a comprehensive discussion of the current challenges facing the future of personal satellite communication systems and some of the proposed solutions. View full abstract»

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  • What if wireless routers were social? approaching wireless mesh networks from a social networks perspective

    Publication Year: 2012 , Page(s): 36 - 43
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (227 KB) |  | HTML iconHTML  

    Wireless mesh networks consist of radio nodes organized in a mesh topology for serving wireless mesh clients to communicate with one another or to connect to the Internet. Nodes in a mesh network can communicate with each other either directly or through one or more intermediate nodes, similar to social networks. WMNs share many common properties with social networks. We first identify the differences and similarities between social networks and WMNs, and then use metrics that are typically used for social network analysis to assess real WMNs. Analyzing real WMN data collected from the University of California at Santa Barbara MeshNet and Massachusetts Institue of Technology Roofnet testbeds reveals that using SNA metrics are helpful in designing WMNs with better performance. We demonstrate the validity of our conclusions and this new approach by focusing on two sample applications: network reliability assessment and channel access scheduling. View full abstract»

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  • Adaptive power management for wireless base stations in a smart grid environment

    Publication Year: 2012 , Page(s): 44 - 51
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (320 KB) |  | HTML iconHTML  

    The growing concerns of a global environmental change leads to a revolution in the way energy is utilized. In the wireless industry, green wireless communications has recently gained increasing attention and is expected to play a major role in the reduction of electrical power consumption. Actions to promote energy saving of wireless communications with regard to environmental protection are becoming imperative. To this purpose, we study a green communications system model where a wireless base station is provisioned with a combination of a renewable power source and the electrical grid to minimize the cost of power consumption as well as meet the users' demand. More specifically, we focus on adaptive power management for a wireless base station under various uncertainties, including renewable power generation, power price, and wireless traffic load. We believe that demand-side power management solutions based on the studied communication architecture is a major step toward green wireless communications. View full abstract»

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  • Relaying technologies for smart grid communications

    Publication Year: 2012 , Page(s): 52 - 59
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (665 KB) |  | HTML iconHTML  

    Wireless technologies can support a broad range of smart grid applications including advanced metering infrastructure and demand response. However, there are many formidable challenges when wireless technologies are applied to the smart gird, such as the trade-offs between wireless coverage and capacity, the high reliability requirement for communication, and limited spectral resources. Relaying has emerged as one of the most promising candidate solutions for addressing these issues. In this article, an introduction to various relaying strategies is presented, together with a discussion of how to improve spectral efficiency and coverage in relay-based information and communications technology infrastructure for smart grid applications. Special attention is paid to the use of unidirectional relaying, collaborative beamforming, and bidirectional relaying strategies. View full abstract»

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  • Toward energy-efficient error control in 3G broadcast video

    Publication Year: 2012 , Page(s): 60 - 67
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (286 KB) |  | HTML iconHTML  

    Energy use is a key issue in battery-operated mobile devices. In order to extend battery life, mobiles showing video often allow a controlled drop in quality, which is tolerable when the shortcomings of a small screen are combined with the imperfections of visual perception. Both energy consumption and video quality are affected by the Reed-Solomon codes and interleaving levels used in 3G video broadcast services. We explore the effect of these elements of MAC-layer error control, and show how they can be manipulated to save energy while maintaining acceptable video quality through a controlled reduction in the number of parity symbols in the Reed-Solomon code and the level of interleaving. View full abstract»

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  • Efficiency of dynamic frequency selection based coexistence mechanisms for tv white space enabled cognitive wireless access points

    Publication Year: 2012 , Page(s): 69 - 75
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1254 KB) |  | HTML iconHTML  

    We investigate the efficiency of dynamic frequency selection (DFS) in mitigating interference among neighboring low-power cognitive wireless portable networks operating in the TV white space. We derive an interference model to predict the range and level of interference generated in the TV bands by portable low-height antenna cognitive wireless access points in suburban and urban areas. Based on the aforementioned model, we provide an analysis of the spectral availability for either the scenarios where DFS coexistence is employed or not. The steps of our analysis are introduced in a tutorial fashion, and a coexistence case study of TVWS enabled low-power cognitive wireless portable APs in Japan is presented. Our analysis demonstrates the intrinsic relationship SA holds with the TVWS channel set as well as statistical information (e.g., household density of wards and cities, Internet penetration, and white space radio AP market penetration). View full abstract»

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  • 3GPP radio resource control in practice

    Publication Year: 2012 , Page(s): 76 - 83
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (243 KB) |  | HTML iconHTML  

    3GPP-standardized networks have been evolving at a very fast pace over the last decade. Cell capacities increased more than an order of magnitude, latencies have become considerably smaller, and worldwide deployment has changed the way people access services. In this evolution, efficient mechanisms for radio resource control have played a key role. In this article we review the RRC state transition model and follow its development from its early stage at the outset of UTRAN deployments to state-of-the art HSPA-enhanced networks. This article also overviews previous work on empirical measurements from 3G networks that study the "theory and practice" of RRC state transitions. Finally, we present our 3G Transition Triggering Tool and use it to empirically study network configuration parameters that prompt RRC transitions. Our results come to the aid of fully understanding the behavior of RRC state transitions and lead us from "theory" to "practice" on RRC mechanisms. View full abstract»

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  • Reconfigurable performance measurement system-on-a-chip for baseband wireless algorithm design and verification

    Publication Year: 2012 , Page(s): 84 - 91
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (752 KB) |  | HTML iconHTML  

    Modern wireless technology applies several powerful but complex techniques - such as multiple-antenna systems, orthogonal frequency-division multiplexing, and capacity-approaching forward error correcting codes - to provide reliable broadband digital communications over the time-varying mobile radio channel. Such techniques appear in most recent wireless standards such as IEEE 802.11n Wi-Fi, IEEE 802.16 WiMax, and 3GPP LTE. Bit error rate simulation continues to be the workhorse design verification and performance optimization methodology; however, the growing complexity of modern wireless systems and the tendency of wireless standards to evolve even after product development has started have greatly increased the required simulation times to the extent that software-based simulation is now the major bottleneck in wireless system development. This article describes how baseband performance verification of wireless systems can be accelerated by over four orders of magnitude using compact, accurate, and high-throughput emulators implemented on reconfigurable field programmable gate arrays. View full abstract»

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  • The COST 2100 MIMO channel model

    Publication Year: 2012 , Page(s): 92 - 99
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (247 KB) |  | HTML iconHTML  

    The COST 2100 channel model is a geometry- based stochastic channel model (GSCM) that can reproduce the stochastic properties of MIMO channels over time, frequency, and space. In contrast to other popular GSCMs, the COST 2100 approach is generic and flexible, making it suitable to model multi-user or distributed MIMO scenarios. In this article a concise overview of the COST 2100 channel model is presented. Main concepts are described, together with useful implementation guidelines. Recent developments, including dense multipath components, polarization, and multi-link aspects, are also discussed. View full abstract»

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  • Energy-efficient cooperative spectrum sensing in sensor-aided cognitive radio networks

    Publication Year: 2012 , Page(s): 100 - 105
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (211 KB) |  | HTML iconHTML  

    Cognitive radio has been proposed to make full use of the limited spectrum resources, where spectrum sensing plays an important role to detect the channel state for opportunistic utilization. To address the hidden terminal problem, cooperative spectrum sensing is employed to improve the detection performance. Due to the energy constraint of battery-powered sensor nodes, energy efficiency emerges as a critical issue in sensor-aided cognitive radio networks. By exploiting the abundant sensor nodes and multiuser diversity, a cooperative schedule of each sensor node's on/off can effectively extend the network lifetime. However, frequent on/off switching of sensor nodes will generate an adverse impact and make the network vulnerable and unreliable. We consider the problem of optimizing the schedule order to reduce the switch frequency. Greedy Heuristic is proposed to approach the minimum node switch with low computational complexity. Simulation results are presented to verify the performance of the proposed algorithm. View full abstract»

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  • Security and privacy of collaborative spectrum sensing in cognitive radio networks

    Publication Year: 2012 , Page(s): 106 - 112
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (286 KB) |  | HTML iconHTML  

    Collaborative spectrum sensing is regarded as a promising approach to significantly improve the performance of spectrum sensing in cognitive radio networks. However, due to the open nature of wireless communications and the increasingly available software defined radio platforms, collaborative spectrum sensing also poses many new research challenges, especially in the aspect of security and privacy. In this article, we first identify the potential security threats toward collaborative spectrum sensing in CRNs. Then we review the existing proposals related to secure collaborative spectrum sensing. Furthermore, we identify several new location privacy related attacks in collaborative sensing, which are expected to compromise secondary users¿ location privacy by correlating their sensing reports and their physical location. To thwart these attacks, we propose a novel privacy preserving framework in collaborative spectrum sensing to prevent location privacy leaking. We design and implement a real-world testbed to evaluate the system performance. The attack experiment results show that if there is no any security guarantee, the attackers could successfully compromise a secondary user¿s location privacy at a success rate of more than 90 percent. We also show that the proposed privacy preserving framework could significantly improve the location privacy of secondary users with a minimal effect on the performance of collaborative sensing. View full abstract»

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  • OFDMA with variable tone spaces

    Publication Year: 2012 , Page(s): 113 - 120
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (252 KB) |  | HTML iconHTML  

    Next generation wireless networks such as 3GPP LTE-A demand enhanced system capacity for high-quality multimedia services. Carrier aggregation based on OFDMA has been introduced to achieve this. In CA, each component carrier can be located on a different frequency band, and each user utilizing it moves at a different speed. This results in different channel characteristics for each user. Enhancing the system capacity in this environment requires a multiple access scheme that considers different channel characteristics among users. However, conventional OFDMA using fixed tone space (called OFDMA-FTS) does not consider user-specific channel characteristics, resulting in capacity degradation. In this article, we propose a new OFDMA system with variable tone spaces (OFDMA-VTS) as an approach to enhance system capacity. OFDMA-VTS selects the tone space suitable for each user by considering userspecific channel characteristics in CA. When intersymbol interference is dominant due to a long delay spread, the small tone space is selected to eliminate severe ISI. Conversely, when intercarrier interference due to a large Doppler spread severely degrades the system performance, the large tone space is selected to compensate ICI. In the proposed OFDMA-VTS, each user adaptively selects the optimal tone space needed to minimize the total interference of ISI and ICI, therefore enhancing system capacity. 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.

Full Aims & Scope

Meet Our Editors

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