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Regulation of spectrum may undergo revolutionary changes in the near future allowing a less restricted and more flexible access to radio spectrum. Intelligent radios, or so-called cognitive radios, will realize the dynamic usage of frequency bands on an opportunistic basis, by identifying and using under-utilized spectrum. Such a flexible spectrum usage requires changes in regulation towards a more...
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 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...
We consider power allocation strategies for radios operating in unlicensed bands. Since each radio's power allocation is a source of interference for other radios sharing the same spectrum, we seek to develop "intelligent" power allocation strategies that not only greedily optimize performance, but also tend toward socially optimal solutions. Radio interaction is modeled as a two-player...
On the views of almost all commentators, the primary obstacle to recognizing property rights in spectrum is either a lack of economic sophistication or political will by the relevant policymakers. To such commentators, the FCC (or a court) could simply enforce property rights at the geographic boundary of a coverage area as well as at the boundaries (or edges) of different frequency bands. The FCC...
Efficient spectrum allocation in open spectrum systems is a challenging problem, particularly for devices with constrained communication resources such as sensor and mobile ad hoc networks. We propose a device-centric spectrum management scheme with low communication costs, where users observe local interference patterns and act independently according to preset spectrum rules. We propose five rules...
Africa, undoubtedly the fastest growing mobile technology market is faced with challenges in the allocation of spectrum. Coping with the astronomical growth in the number of the spectrum users and effect of the mode of implementation of spectrum allocation to users has been a burden in terms of cost for the service provider in the cellular industry. Since the spectrum can be re-used by the service...
In established communication systems the price is determined quasi-static and for a large area according to a fixed price model. Additionally, the main decision criterion of resource allocation is the arrival time of resource requests. This system approach is not able to respond to the spatial distributed and dynamic users' demand and willingness-to-pay. In this paper a system will be proposed to...
This paper introduces a new wireless architecture that creates ultimate freedom for dynamic channel allocation (DCA). The architecture is implemented based on the capabilities of cognitive radios. In the current wireless systems, users should subscribe to a service provider (vendor) and receive the service through the spectrum assigned to that vendor at all times. Hence, we call the current wireless...
We consider a spectrum sharing problem in which each wireless transmitter can select a single channel from a set of available channels, along with the transmission power. An asynchronous distributed pricing (ADP) scheme is proposed, in which users exchange "price" signals that indicate the negative effect of interference at the receivers. Given this set of prices, each transmitter chooses...
In this paper we discuss distributed spectrum allocation techniques in interference limited environment. We analyze the well known iterative water-filling strategy for a simplified two players interference game, and provide closed form analysis of the cases in which the IWF is suboptimal due to the occurrence of the well known prisoner's dilemma. We then propose some alternative distributed coordination...
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...
We consider a centralized spectrum server that coordinates the transmissions of a group of links sharing a common spectrum. Links employ on-off modulation with fixed transmit power when active. In the on state, a link obtains a data rate determined by the signal-to-interference ratio on the link. By knowing the link gains in the network, the spectrum server finds an optimal schedule that maximizes...
We report sensitive spectrum measurements from 70 to 1500 MHz of the radio interference (RFI) environment at locations in Westford, Massachusetts and Hancock, New Hampshire. These measurements show that below 400 MHz the interference in bands allocated to passive services is often limited by unintentional signals from power lines and part 15 devices
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,...
Traditionally, frequency spectrum is licensed to users by government agencies in a fixed manner where licensee has exclusive right to access the allocated band. This policy has been de jure practice to protect systems from mutual interference for many years. However, with increasing demand for the spectrum and scarcity of vacant bands, a spectrum policy reform seems inevitable. Meanwhile, recent measurements...
In cognitive networks, cognitive (unlicensed) users need to continuously monitor spectrum to detect the presence of primary (licensed) users. In this paper, we illustrate the benefits of cooperation in cognitive radio. We show that by allowing the cognitive radios operating in the same band to cooperate we can reduce the detection time and thus increasing their agility. We first consider the case...
Channel sensing and spectrum allocation has long been of interest as a prospective addition to cognitive radios for wireless communications systems occupying license-free bands. Conventional approaches to cyclic spectral analysis have been proposed as a method for classifying signals for applications where the carrier frequency and bandwidths are unknown, but is, however, computationally complex and...
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...
Today, the largest and most desirable portion of the radio spectrum is allocated to licensed services, which has resulted in the well-known profound scarcity of this resource for emerging applications. With the rapid growth of wireless technologies, current spectrum scarcity has become a serious problem as more and more wireless applications compete for very little spectrum. On the other hand, the...
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