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Selected Areas in Communications, IEEE Journal on

Issue 3 • Date April 2007

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Displaying Results 1 - 24 of 24
  • Table of Contents (1 of 2) - April 2007, Vol 25 No 3

    Page(s): c1
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    Freely Available from IEEE
  • IEEE Communications Society [Inside front cover]

    Page(s): c2
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    Freely Available from IEEE
  • Guest Editorial - Adaptive, spectrum agile and cognitive wireless networks

    Page(s): 513 - 516
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    The 11 papers in this special issue focus on adaptive, spectrum agile and cognitive wireless networks. Some of the topics covered include: fundamental performance aspects of spectrum sharing; spectrum sensing capabilities in cognitive radios; detection and estimation approaches to spectrum sharing; MAC design in opportunistic spectrum access; and competitive spectrum sharing and resource allocation using concepts from game theory and pricing. View full abstract»

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  • Spectrum sharing for unlicensed bands

    Page(s): 517 - 528
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    We study a spectrum sharing problem in an unlicensed band where multiple systems coexist and interfere with each other. Due to asymmetries and selfish system behavior, unfair and inefficient situations may arise. We investigate whether efficiency and fairness can be obtained with self-enforcing spectrum sharing rules. These rules have the advantage of not requiring a central authority that verifies compliance to the protocol. Any self-enforcing protocol must correspond to an equilibrium of a game. We first analyze the possible outcomes of a one shot game, and observe that in many cases an inefficient solution results. However, systems often coexist for long periods and a repeated game is more appropriate to model their interaction. In this repeated game the possibility of building reputations and applying punishments allows for a larger set of self-enforcing outcomes. When this set includes the optimal operating point, efficient, fair, and incentive compatible spectrum sharing becomes possible. We present examples that illustrate that in many cases the performance loss due to selfish behavior is small. We also prove that our results are tight and quantify the best achievable performance in a non-cooperative scenario View full abstract»

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  • Capacity limits of cognitive radio with distributed and dynamic spectral activity

    Page(s): 529 - 537
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (835 KB) |  | HTML iconHTML  

    We investigate the capacity of opportunistic communication in the presence of dynamic and distributed spectral activity, i.e., when the time varying spectral holes sensed by the cognitive transmitter are correlated but not identical to those sensed by the cognitive receiver. We develop a two switch model that captures the localized spectral activity estimates at the transmitter and receiver. The information theoretic framework of communication with side information is employed to characterize the capacity of the cognitive link with both causal and non-causal side information at the transmitter and/or the receiver. These capacity results are used to determine the benefits of any feedforward and feedback information. We find that cognitive radio capacity is robust to the uncertainties arising out of distributed and dynamic spectral environments, even when the communication occurs in bursts of only 3-5 symbols. The capacity depends strongly on the correlation of the local spectral environment at the cognitive transmitter and receiver. View full abstract»

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  • An adaptive weaver architecture radio with spectrum sensing capabilities to relax RF component requirements

    Page(s): 538 - 545
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    This paper presents an architecture that utilizes spectrum sensing with a Weaver architecture receiver to ease the requirements on the RF front-end components. With the ability to sense the environment, large interferers that overwhelm small desired signals can be avoided. The learning and adapting capabilities are enabled by means of a flexible receiver architecture employing variable local oscillators (LOs) at RF and intermediate frequency (IF). Avoiding large interferers can reduce image rejection ratio (IRR) requirements for a given performance and results in a greater tolerance to the Q of filters and receiver mismatches. The design approach is applied to an IEEE 802.11a receiver and the results show that for a given performance level, the proposed design requires an IRR that is 40 dB less than that required for conventional Weaver receivers View full abstract»

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  • Spectrum sensing: A distributed approach for cognitive terminals

    Page(s): 546 - 557
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    Cognitive radios is emerging in research laboratories as a promising wireless paradigm, which will integrate benefits of software defined radio with a complete aware communication behavior. To reach this goal many issues remain still open, such as powerful algorithms for sensing the external environment. This paper presents a further step in the direction of allowing cooperative spectrum sensing in peer-to-peer cognitive networks by using distributed detection theory. The approach aims at improving the radio awareness with respect to stand alone scenario as it is shown with theoretical and experimental results View full abstract»

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  • On the extraction of the channel allocation information in spectrum pooling systems

    Page(s): 558 - 565
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    The spectrum pooling strategy allows a license owner to share a part of his licensed spectrum with a secondary wireless system (the rental system, RS) during its idle times. The coexistence of two mobile systems on the same frequency band poses many new challenges, one of which is the reliable extraction of the channel allocation information (CAI), i.e. the channel occupation of the licensed system (LS). This paper presents a strategy for the extraction of the CAI based on exploiting the distinct cyclostationary characteristics of the LS and RS signals and demonstrates, via simulations, its application on a specific spectrum pooling scenario, where the LS is a GSM network and the RS is an OFDM based WLAN system View full abstract»

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  • Robust joint interference detection and decoding for OFDM-based cognitive radio systems with unknown interference

    Page(s): 566 - 575
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (551 KB) |  | HTML iconHTML  

    Cognitive radio technology facilitates spectrum reuse and alleviates spectrum crunch. One fundamental problem in cognitive radio is to avoid the interference caused by other communication systems sharing the same frequency band. However, spectrum sensing cannot guarantee accurate detection of the interference in many practical situations. Hence, it is crucial to design robust receivers to combat the in-band interference. In this paper, we first present a simple pilot aided interference detection method. To combat the residual interference that cannot be detected by the interference detector, we further propose a robust joint interference detection and decoding scheme. By exploiting the code structure in interference detection, the proposed scheme can successfully detect most of the interfered symbols without requiring the knowledge of the interference distribution. Our simulation results show that, even without any prior knowledge of the interference distribution, the proposed joint interference detection and decoding scheme is able to achieve a performance close to that of the maximum likelihood decoder with the full knowledge of the interference distribution View full abstract»

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  • What and how much to gain by spectrum agility?

    Page(s): 576 - 588
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (601 KB) |  | HTML iconHTML  

    Static spectrum allocation prohibits radio devices from using spectral bands designated for others. As a result, some bands are under-utilized while other bands are over-populated with radio devices. To remedy this problem, the concept of spectrum agility has been considered so as to enable devices to opportunistically utilize others' spectral bands. In order to help realize this concept, we establish an analytical model to derive performance metrics, including spectrum utilization and spectrum-access blocking time in spectral-agile communication systems. We then propose three basic building blocks for spectral-agile systems, namely spectrum opportunity discovery, spectrum opportunity management, and spectrum usage coordination, and develop protocols for each blocks. These protocols are integrated with the IEEE 802.11 protocol, and simulated using ns-2 to evaluate the protocol overhead. The simulation results show that our proposed protocols can improve the throughput of an IEEE 802.11 wireless LAN by 90% for the simulated scenarios, and the improvements matched well our analytical model. These results demonstrate the great potential of using spectrum agility for improving spectral utilization in an efficient, distributed, and autonomous manner View full abstract»

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  • Decentralized cognitive MAC for opportunistic spectrum access in ad hoc networks: A POMDP framework

    Page(s): 589 - 600
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    We propose decentralized cognitive MAC protocols that allow secondary users to independently search for spectrum opportunities without a central coordinator or a dedicated communication channel. Recognizing hardware and energy constraints, we assume that a secondary user may not be able to perform full-spectrum sensing or may not be willing to monitor the spectrum when it has no data to transmit. We develop an analytical framework for opportunistic spectrum access based on the theory of partially observable Markov decision process (POMDP). This decision-theoretic approach integrates the design of spectrum access protocols at the MAC layer with spectrum sensing at the physical layer and traffic statistics determined by the application layer of the primary network. It also allows easy incorporation of spectrum sensing error and constraint on the probability of colliding with the primary users. Under this POMDP framework, we propose cognitive MAC protocols that optimize the performance of secondary users while limiting the interference perceived by primary users. A suboptimal strategy with reduced complexity yet comparable performance is developed. Without additional control message exchange between the secondary transmitter and receiver, the proposed decentralized protocols ensure synchronous hopping in the spectrum between the transmitter and the receiver in the presence of collisions and spectrum sensing errors View full abstract»

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  • Mechanism-based resource allocation for multimedia transmission over spectrum agile wireless networks

    Page(s): 601 - 612
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB) |  | HTML iconHTML  

    We propose to add a new dimension to existing wireless multimedia systems by enabling autonomous stations to dynamically compete for communication resources through adjustment of their internal strategies and sharing their private information. We focus on emerging spectrum agile wireless networks, where developing an efficient strategy for managing available communication resources is of high importance. The proposed dynamic resource management approach for wireless multimedia changes the passive way stations are currently adapting their joint source-channel coding strategies according to available wireless resources. Each wireless station can play the resource management game by adapting its multimedia transmission strategy depending on the experienced channel conditions and user requirements. The resource allocation game is coordinated by a network moderator, which deploys mechanism-based resource management to determine the amount of transmission time to be allocated to various users on different frequency bands such that certain global system metrics are optimized. Subsequently, the moderator charges the various users based on the amount of resources it has allocated to them, in order to discourage them from being dishonest about their resource requirements. We investigate and quantify both the users' and the system performance when different cross-layer strategies, and hence users' levels of smartness, are deployed by wireless stations. Our simulations show that mechanism-based resource management outperforms conventional techniques such as air-fair time and equal time resource allocation in terms of the obtained system utility. They also provide insights that can guide the design of emerging spectrum agile network protocols and applications View full abstract»

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  • Price dynamics in competitive agile spectrum access markets

    Page(s): 613 - 621
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    We explore the price dynamics in a competitive market consisting of spectrum agile network service providers and users. Here, multiple self interested spectrum providers operating with different technologies and costs compete for potential customers. Different buyers or consumers may evaluate the same seller differently depending on their applications, operating technologies and locations. Two different buyer populations, the quality-sensitive and the price-sensitive are investigated, and the resulting collective price dynamics are studied using a combination of analysis and simulations. Various scenarios are considered regarding the nature and accuracy of information available to the sellers. A myopically optimal strategy is studied when full information is available, while a stochastic learning based strategy is considered when the information is limited. Cooperating groups may be formed among the sellers which will in-turn influence the group profit for those participants. Free riding phenomenon is observed under certain circumstances View full abstract»

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  • Public safety and commercial spectrum sharing via network pricing and admission control

    Page(s): 622 - 632
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (498 KB) |  | HTML iconHTML  

    Public safety and commercial communications have distinct performance objectives. The former requires a high availability (i.e., low blocking), both in normal times and during a disaster, whereas the latter requires a high network revenue performance in normal times. Therefore, public safety and commercial communications traditionally use separate networks, which results in either spectrum inefficiency or unsatisfactory performance. In this paper, we propose a public safety and commercial spectrum sharing strategy via intelligent network pricing and call admission control. We provide a precise characterization of the performance objectives of such a sharing strategy, which is to maximize the commercial revenue while guaranteeing a low blocking probability to public safety calls. We demonstrate through analysis and simulation that our sharing strategy simultaneously satisfies the objectives of both types of communications View full abstract»

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  • Call for Papers - Control and Communications

    Page(s): 633
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  • Call for Papers - IEEE Journal on Selected Areas in Communications - Multiuser Detection for Advanced Communication Systems and Networks

    Page(s): 634
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    Freely Available from IEEE
  • Call for Papers - Delay and Disruption Tolerant Wireless Communication

    Page(s): 635
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    Freely Available from IEEE
  • Call for Papers - MIMO for Next-Generation Wireless Networks

    Page(s): 636
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    Freely Available from IEEE
  • Call for Papers - Game Theory in Communication Systems

    Page(s): 637
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  • Call for Papers - IEEE Journal of Selected Areas in Communications - Exploiting Limited Feedback in Tomorrow's Wireless Communication Networks

    Page(s): 638
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  • Information for Authors - IEEE Journal on Selected Areas in Communication (J-SAC)

    Page(s): 639
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    Provides instructions and guidelines to prospective authors who wish to submit manuscripts. View full abstract»

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  • Tutorials Now - Online Tutorials [advertisement]

    Page(s): 640
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    Freely Available from IEEE
  • IEEE Communications Society - 2007 Board of Governors [Inside Back Cover]

    Page(s): c3
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  • Table of Contents (2 of 2) - April 2007, Vol 25 No 3

    Page(s): c4
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    Freely Available from IEEE

Aims & Scope

IEEE Journal on Selected Areas in Communications focuses on all telecommunications, including telephone, telegraphy, facsimile, and point-to-point television, by electromagnetic propagation.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Muriel Médard
MIT