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Three spectrum sharing schemes-spreading-based underlay, interference avoidance (IA) based overlay and spreading-based underlay that implements IA, are compared in this paper. The comparison is based on the influence of these techniques on the performance of an existing legacy static radio system with which the spectrum-sharing radios coexist. Outage probability is used to evaluate the performance...
In this paper we develop a framework for competition of future operators likely to operate in a mixed commons/property-rights regime under the regulation of a spectrum policy server (SPS). The operators dynamically compete for customers as well as portions of available spectrum. The operators are charged by the SPS for the amount of bandwidth they use in their services. Through demand responsive pricing,...
Preliminary studies as well as general observations indicate the presence of a significant amount of "white space" in radio spectrum, varying on frequency, time, and geographic locations. Thus, it is likely that spectrum access, instead of true spectrum scarcity, is the limiting factor of potential growth of wireless services. Enabled by regulatory changes and radio technologies advances,...
Dynamic spectrum access networks and spectrum policy depend on accurate spectrum utilization statistics. This paper presents the architecture of a collaborative framework to measure, characterize and model the utilization of the spectrum. It provides statistical methods to classify measurements as either signal or noise. Finally, it introduces algorithms for estimating signal thresholds and spectrum...
The migration of telecommunications towards the B3G era is characterized by the convergence of mobile communication systems and IP networks, in order to better adapt to the-continuously increasing-user demands. Reconfigurability constitutes a major facilitator towards such convergence. However, the introduction of such concept can change the way wireless networks are designed, due to the time-variant...
Certification and assurance processes have historically exhibited difficulties when there exists the potential for significant non-functional attributes. We define a non-functional attribute as a condition where the cause-effect behavior cannot readily be specified. Complex systems commonly exhibit such non-functional attributes due to the exceedingly large potential state space. In such systems,...
In this paper we present node architecture for a personal node in a cognitive ad-hoc disaster relief network. This architecture is motivated from the network system requirements, especially single-hop distance and jamming-resilience requirements. It is shown that the power consumption of current-day analog to digital converters (ADCs) limits the channel bandwidth that can be used, both for a baseband...
Cognitive radios have been advanced as a technology for the opportunistic use of under-utilized spectrum. Cognitive radio is able to sense the spectrum and detect the presence of primary users. However, primary users of the spectrum are skeptical about the robustness of this sensing process and have raised concerns with regards to interference from cognitive radios. Furthermore, while a number of...
To address the recent FCC initiatives that encourage the use of locally unused or under-used television broadcast spectrum for unlicensed broadband wireless access, a cognitive-enabled experimental system was developed to explore secondary spectrum utilization and user coordination through autonomous operation on a non-interference basis. This paper describes the enabling technologies and concepts,...
This paper investigates the performance of FFT- type feature TV detector of weak signals, which can be used in listen-before-talk (LBT) spectrum access algorithms. Using FFT plots applied to consecutive sets of measurements collected at multiple locations, we illustrate and characterize different types of spurious signal environments. Ultra sensitive TV detectors can significantly improve the overall...
Recent FCC proceedings have considered the notion of unlicensed device operation in licensed bands. Licensed users are concerned about harmful interference while unlicensed device manufacturers are concerned that harmful interference is an imprecise design concept. This paper addresses three elements to this debate. First, it advocates for an explicit model of harmful interference to be included in...
This paper presents a definition and framework for a novel type of adaptive data network: the cognitive network. In a cognitive network, the collection of elements that make up the network observes network conditions and then, using prior knowledge gained from previous interactions with the network, plans, decides and acts on this information. Cognitive networks are different from other "intelligent"...
An autonomous dynamic spectrum access (ADSA) system overcomes the spectrum scarcity caused by the current command and control spectrum allocation paradigm, by enabling multiple uncoordinated groups of radios to access spectrum on an as-needed basis without causing mutual harmful interference. This paper describes the behavior and performance of such a system. Adaptation is driven by continual monitoring...
The traditional approach to managing radio frequency (RF) spectrum concludes with a spectrum management administration identifying how a band of spectrum may be used in a region it administers and who may use it. This approach to spectrum management is encumbered with political process that is challenged to keep pace with the rapid advances in technologies that exploit RF spectrum. Recognizing that...
Recent study by FCC spectrum policy task force (SPTF) found that while the available spectrum becomes increasingly scarce, the assigned spectrum is significantly underutilized. Cognitive radio technology holds the key promise to solve such problems. In this paper, we investigate some physical layer issues of wide-band cognitive radio systems. Specifically, we discuss the physical layer signal structure...
Most of the study of implementing cognitive radio technology to date has focused on its potential in military and emergency services uses. This paper examines some of the issues involved in adapting cognitive radio technology consumer markets. We highlight some potential advantages to cognitive radio defined networks for consumers and suggest some possible service designs and pricing systems
This article reviews the various approaches to dynamic sharing of spectrum that have been employed over time, identifies the costs and benefits of these approaches, and offers conclusions on the characteristics of radio services that benefit most from the use of dynamic sharing. Dynamic sharing is a powerful tool for spectrum management. It offers the opportunity for substantial efficiency gains....
This paper looks at the regulatory changes that are required to allow technologies such as DySPAN quick and easy access to radio spectrum. Without such changes, it will not be possible for DySPAN technologies to make the inroads into the market that are required to ensure spectrum is used with the optimum economic efficiency. This access to market requires greater use of a technology neutral spectrum...
Device coordination in open spectrum systems is a challenging problem, particularly since users experience varying spectrum availability over time and location. We propose a distributed coordination approach that handles spectrum heterogeneity without relying on the existence of a preassigned common control channel. Our approach carries potential to provide robust operation under network dynamics...
We consider the problem of opportunistic dynamic spectrum access (DSA) in an ad hoc network in which unlicensed secondary users communicate through channels not used by the primary users. Decentralized cognitive medium access control protocols are presented that allow secondary users to recognize spectrum opportunity and transmit based on a partial observation of the instantaneous spectrum availability...
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