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New Frontiers in Dynamic Spectrum Access Networks, 2007. DySPAN 2007. 2nd IEEE International Symposium on

Date 17-20 April 2007

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Displaying Results 1 - 25 of 90
  • [Title page - DYSPAN 2007]

    Page(s): c1
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  • [Copyright notice - DYSPAN 2007]

    Page(s): ii
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  • General Chair Message - DYSPAN 2007

    Page(s): iii
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  • Technical Chair Message - DYSPAN 2007

    Page(s): iv
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  • Policy Chairmen Welcome - DYSPAN 2007

    Page(s): v
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  • Report from the Patron and Sponsorship Committee Chair - DYSPAN 2007

    Page(s): vi
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  • Committees - DYSPAN 2007

    Page(s): vii - x
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  • Sponsors - DYSPAN 2007

    Page(s): xi - xii
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  • Table of contents - DYSPAN 2007

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  • A Description of the August 2006 XG Demonstrations at Fort A.P. Hill

    Page(s): 1 - 12
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1849 KB) |  | HTML iconHTML  

    On Aug 15-17, 2006, Shared Spectrum Company (SSC) and the U.S. Department of Defense's Defense Advanced Research Projects Agency (DARPA) demonstrated, for the first time, a six node network of next generation (XG) radios capable of using spectrum over a wide range of frequencies on a secondary basis. The cognitive radios making up several formations of XG networks sensed radio signals over 225-600 MHz and adapted frequencies automatically to prevent interference to existing military and civilian radio systems. The XG networks were tested on a military test range (Fort A.P. Hill, Bowling Green, VA) in front of an audience of over one hundred military and government spectrum management agency representatives from the Army, Navy, Air Force, Coast Guard, Joint Spectrum Center, the Federal Communications Commission and the National Telecommunications and Information Administration. This paper describes the XG radio system and test scenarios. A companion paper presents a detailed account of the test results. View full abstract»

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  • A Game-Theoretic View on the Interference Channel with Random Access

    Page(s): 13 - 21
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (373 KB) |  | HTML iconHTML  

    As an important building block of cognitive radio networks, the interference channel with distributed and competing radio access is currently an active area of research. In this work, a basic two-by-two interference channel is studied by considering random packet arrivals and random access. In particular, each transmitter is assumed to select independently and concurrently a transmission probability based on the state of the system queues. Both the cases of perfect and partial information about the transmitters' backlogs are addressed. The system is analyzed using tools from game theory, and specifically from the theory of stochastic games. The main conclusion is that random packet arrival has a beneficial effect on the efficiency of decentralized random access. This result is achieved by comparing the efficiency of Nash equilibria for the case of backlogged users with the corresponding equilibria in presence of random packet arrivals via numerical simulations. View full abstract»

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  • A General Framework for Wireless Spectrum Auctions

    Page(s): 22 - 33
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB) |  | HTML iconHTML  

    We propose a real-time spectrum auction framework to distribute spectrum among a large number wireless users under interference constraints. Our approach achieves conflict-free spectrum allocations that maximize auction revenue and spectrum utilization. Our design includes a compact and yet highly expressive bidding language, various pricing models to control tradeoffs between revenue and fairness, and fast auction clearing algorithms to compute revenue-maximizing prices and allocations. Both analytical and experimental results verify the efficiency of the proposed approach. We conclude that bidding behaviors and pricing models have significant impact on auction outcomes. A spectrum auction system must consider local demand and spectrum availability in order to maximize revenue and utilization. View full abstract»

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  • A Location-Based Method for Specifying RF Spectrum Rights

    Page(s): 34 - 45
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (529 KB) |  | HTML iconHTML  

    We provide a method to specify location based spectrum rights that enables spectrum management with finer resolution in space and frequency. This method accounts for the attenuation of transmissions from their source and so reveals the location based opportunities to reuse spectrum. The method uses a concise yet flexible data structure that has six parts: a signal strength, a frequency, a spectrum mask, a power map, a propagation map, and a scaling factor. Through the use of one or multiple of these parts most any type of spatial spectrum use authorization or protection may be defined. The structure allows spectrum to be managed as a spatial resource and so subdivided for spatial reuse or for resale. We provide several examples to demonstrate its versatility in spectrum management. We provide some observations and theorems that are useful in developing algorithms to verify compliance to the rights and restrictions conveyed in the proposed method and to discern when coexistent spectrum use is possible. This method provides a unified approach to define spectrum use that can be used to license spectrum, to optimize spectrum reuse, to negotiate spectrum rights, and to specify spectrum policy. It is ideally suited for over-the-air management of spectrum use. View full abstract»

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  • A novel on-demand cognitive pilot channel enabling dynamic spectrum allocation

    Page(s): 46 - 54
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (332 KB) |  | HTML iconHTML  

    This paper addresses the implementation of the cognitive pilot channel (CPC), which has been recently proposed as a solution to assist the mobile reconfigurable and cognitive terminals in heterogeneous wireless scenarios with different access networks available and varying spectrum allocations. The paper describes the operation of the CPC and the different approaches existing in the literature depending on how it is mapped onto specific radio resources. Then, it focuses on the implementation of the CPC information delivery and proposes the use of an on-demand CPC, which requires a significantly lower bit rate than the broadcast approach to achieve similar performance. View full abstract»

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  • A Policy Engine for Spectrum Sharing

    Page(s): 55 - 65
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (684 KB) |  | HTML iconHTML  

    We argue for a policy-based approach to increase spectrum availability. To this extend, we briefly summarize a new language for expressing policies that allow opportunistic spectrum access. A Policy Reasoner that reasons about these policies can be used with cognitive radios to guarantee policy- specified behaviors while allowing spectrum sharing. We present our policy reasoner design and we evaluated the reasoner in a demonstration. We describe the policies used in that demonstration and the results of the evaluation. View full abstract»

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  • A Policy Proposal to Enable Cognitive Radio for Public Safety and Industry in the Land Mobile Radio Bands

    Page(s): 66 - 77
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (283 KB) |  | HTML iconHTML  

    The frequency bands that have been licensed to the land mobile radio (LMR) services for decades are a tremendously fertile field for the deployment of cognitive radio technology. This paper outlines several reasons why policy-based cognitive radios would be particularly useful for modern public safety, federal non-military and business/industrial applications, especially in the VHF and UHF bands, where 80% of the public safety, federal and business/industrial licenses are currently held. This paper argues that many interoperability deficiencies are directly related to the original approach to spectrum policy and radio frequency regulation developed in the early 1920's, which segmented uses of LMR spectrum into several use classes. It provides a historic perspective to explain why the current status of LMR infrastructure, operations and licensee behavior is a direct result of antiquated policies and technologies still applied and deployed in these bands. The paper discusses the reasons that cognitive radio could be a successful solution for the apparent congestion in the bands. It suggests that policy-based cognitive radio systems operated on a cooperative, shared basis could lower costs of use and aid coordination for emergency responders across both public and private sectors of the traditional LMR user community. We discuss policy reforms and innovations such as spectrum pooling and spectrum portability that could spur new shared infrastructure development and spectrum efficiencies. We suggest several key policy reforms for consideration, including immediate cessation of ongoing narrowbanding initiatives, decoupling of spectrum licenses from spectrum access, and national spectrum management by frequency coordinators. View full abstract»

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  • Adaptive Positioning Systems for Cognitive Radios

    Page(s): 78 - 84
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (173 KB) |  | HTML iconHTML  

    Location awareness is a prominent characteristic of cognitive radio technologies. Realizing such awareness in cognitive radios require an underlying advanced positioning system that have cognition capabilities. In this paper, an innovative cognitive positioning system (CPS) that have cognition capabilities by means of adjusting positioning accuracy adaptively in both indoor and outdoor environments is proposed. Bandwidth determination and hybrid overlay and underlay enhanced dynamic spectrum management (H-EDSM) are two main components that form the proposed CPS technique. Bandwidth determination equations are derived through Cramer-Rao lower bound (CRLB) for additive white Gaussian noise (AWGN). H-EDSM that provides optimum available bandwidth to the CPS is proposed. A switching mechanism that manages the transition between overlay and underlay spectrum usage modes for the H-EDSM algorithm is presented. Theoretical analysis of the mechanism is carried out using two-slope model. Simulation results, challenges and complexity options for the implementation of the CPS are outlined. Our study reveals the existence of a trade-off between accuracy and complexity in the adaptive positioning systems for cognitive radios. View full abstract»

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  • An Autonomous Adaptive Base Station that Supports Multiple Wireless Network Systems

    Page(s): 85 - 88
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (407 KB) |  | HTML iconHTML  

    Various wireless systems are being developed to meet users' needs, and effective frequency use is urgently needed because of the rapid increase in frequency demand that accompanies the increasing popularity of wireless services. However, general base stations are making no effort to use frequency effectively, and cooperation among wireless system base stations is necessary for more effective frequency use. Base stations can cooperate more efficiently if they are able to use multiple channels of many wireless systems simultaneously. In this paper, we propose an autonomous adaptive base station (AABS) that adapts to various wireless systems the way software defined radio (SDR) base stations do. The AABS can autonomously select and use the most suitable wireless system based on user traffic and AABS's hardware resources. AABS can also offer a communication environment suitable for "multi-link communication", because AABS can use multiple channels of multiple wireless systems simultaneously. We developed an AABS prototype so we could evaluate performance. Our experimental and computer simulation results demonstrate that the prototype performs effectively. View full abstract»

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  • An Economic Framework for Spectrum Allocation and Service Pricing with Competitive Wireless Service Providers

    Page(s): 89 - 98
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (213 KB) |  | HTML iconHTML  

    In the future, we can expect to see more dynamic service offerings and profiles, as users move from long-term service provider agreements to more opportunistic service models. Moreover, when the radio spectrum is itself traded in a market- based scenario, wireless service providers (WSPs) will likely require new strategies to deploy services, define service profiles, and price them. Currently, there is little understanding on how such a dynamic trading system will operate so as to make the system feasible under economic terms. From an economic point of view, we analyze two main components of this overall trading system: (i) spectrum allocation to WSPs and (ii) interaction of end users with the WSPs. For this two-tier trading system, we present a winner determining sealed-bid knapsack auction mechanism that dynamically allocates spectrum to the WSPs based on their bids. We propose a dynamic pricing strategy based on game theory to capture the conflict of interest between WSPs and end users, both of whom try to maximize their respective net utilities. We show that even in such a greedy and non-cooperative behavioral game model, it is in the best interest of the WSPs to adhere to a price threshold which is a consequence of a price equilibrium in an oligopoly situation. Through simulation results, we show that the proposed auction entices the WSPs to participate in the auction, makes optimal use of the common spectrum pool, and avoids collusion among WSPs. Moreover, numerical results demonstrate how pricing can be used as an effective tool for providing incentives to the WSPs to upgrade their network resources and offer better services. View full abstract»

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  • Analysis of Communication Opportunities in UMTS Cellular Networks

    Page(s): 99 - 102
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (414 KB) |  | HTML iconHTML  

    A scenario based on an UMTS TDD opportunistic cellular system that operates over UMTS FDD licensed cellular networks is considered. Therefore a simulation tool was developed for the analysis and assessment of UMTS TDD opportunistic radio system in a coexistence environment with UMTS FDD primary cellular networks. The communication presents the scenario considered, the main features of the simulation tool, discusses and proposes metrics to evaluate the communication opportunities in UMTS FDD primary cellular networks, and presents numerical simulation results. These show that a moderate number of UMTS FDD available frequencies and a reasonable UMTS TDD opportunistic radio transmission power will allow the deployment of UMTS TDD opportunistic radio networks in a coexistence environment with existing licensed systems. View full abstract»

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  • Applications of Topology Information for Cognitive Radios and Networks

    Page(s): 103 - 114
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (351 KB) |  | HTML iconHTML  

    The cognitive radio is a strong and promising paradigm for the next generation self-adaptive smart radios and networks. In this paper we study the potential applications of the topology information in a cognitive radio environment. We argue that use of network topology information, including here the geometric relations of the nodes, can bring significant benefits to cognitive radios and networks. We believe that in the case of wireless networks, and especially in the case of cooperative cognitive radios, it is extremely valuable to know more about the network topology than just neighbourhood counts. The topology information has direct usage and implications on connectivity and capacity estimates of the network, and is a key quantity to consider in making of network optimization decisions. As a "proof of concept" for out ideas, we present a rather detailed and comprehensive topology information characterization study using spatial statistic models. We introduce particularly N-point spatial correlation functions and demonstrate their usability. Furthermore we report new results on correlated locations on WiFi access point locations as an example. View full abstract»

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  • Applying Radio Environment Maps to Cognitive Wireless Regional Area Networks

    Page(s): 115 - 118
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (308 KB) |  | HTML iconHTML  

    The IEEE 802.22 wireless regional area network (WRAN) is the first worldwide commercial application of cognitive radio (CR) networks refarming the TV broadcast bands. According to US FCC's recent public notice, WRAN products are scheduled to be available for the market by February, 2009. This paper first presents a brief review of the IEEE 802.22 WRAN standardization, and then introduces the radio environment map (REM) as an innovative cost-efficient approach to developing and managing WRAN systems. REMs can provide powerful infrastructure support to the functionality of the WRAN cognitive engine (CE). The data model of the REM is presented together with an extensive discussion on how to exploit the REM for a variety of applications in WRAN systems, focusing on the REM-enabled case- and knowledge-based learning algorithms (REM-CKL) for WRAN CEs. Furthermore, REM-based radio scenario-driven testing (REM-SDT) is also presented as a viable approach to evaluating the performance of CEs. Future research topics are discussed in the final section. View full abstract»

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  • Blind OFDM Systems Parameters Estimation for Software Defined Radio

    Page(s): 119 - 122
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (156 KB) |  | HTML iconHTML  

    In this paper, a blind OFDM system parameters estimation method for software defined radio (SDR) is proposed. This method sequentially estimate the sampling frequency, the number of subcarriers, the CP length as well as the timing and frequency offset in OFDM systems. The blind estimation is based on a combination of the cyclostationarity test and correlation. Monte Carlo simulation is employed to test the performance of the individual estimators as well as the whole estimator. View full abstract»

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  • Can Cognitive Radio Support Broadband Wireless Access?

    Page(s): 123 - 132
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (245 KB) |  | HTML iconHTML  

    One application of cognitive radios is to provide broadband wireless access (BWA) in the licensed TV bands on a secondary access basis. This concept is examined to see under what conditions BWA could be viable. Rural areas require long range communication which cognitive radios may not be able to support with enough secondary spectrum. Urban areas have less available spectrum and the BWA must use shorter ranges with greater spatial reuse. Furthermore, it is not clear what regulatory model would best support BWA. This paper considers demographic (urban, rural) and licensing (unlicensed, nonexclusive licensed, exclusive licensed) dimensions. A general BWA efficiency and economic analysis tool is developed and then example parameters corresponding to each of these regimes are derived. The results indicate that in rural areas an unlicensed model is viable and the additional spectrum would be useful despite existing unlicensed spectrum. In the densest urban areas the licensed models are not viable. This is not simply because there is less unused spectrum in urban areas. Urban area cognitive radios are constrained to short ranges and many broadband alternatives already exist. As a result the cost per subscriber is high. An unlicensed model is viable in urban areas, however the spectrum needs can be met with existing unlicensed spectrum. These results provide useful input for a variety of spectrum policy issues. View full abstract»

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  • Channel Selection Under Interference Temperature Model in Multi-Hop Cognitive Mesh Networks

    Page(s): 133 - 136
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (202 KB) |  | HTML iconHTML  

    A cooperative algorithm based on interference temperature model is proposed for computation of available channels by mesh nodes in a cognitive mesh network. Interference temperature model is used to model occupancy and availability of a channel. Link and end-to-end routing metrics are proposed to select appropriate channels from the computed set of available channels. View full abstract»

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