The Challenge of Increasing Broadband Capacity

Symposium: Essays from Time Warner Cable\u27s Research Program on Digital Communications

Scalar Perturbations in Scalar Field Quantum Cosmology

In this paper it is shown how to obtain the simplest equations for the Mukhanov-Sasaki variables describing quantum linear scalar perturbations in the case of scalar fields without potential term. This was done through the implementation of canonical transformations at the classical level, and unitary transformations at the quantum level, without ever using any classical background equation, and it completes the simplification initiated in investigations by Langlois \cite{langlois}, and Pinho and Pinto-Neto \cite{emanuel2} for this case. These equations were then used to calculate the spectrum index $n_s$ of quantum scalar perturbations of a non-singular inflationary quantum background model, which starts at infinity past from flat space-time with Planckian size spacelike hypersurfaces, and inflates due to a quantum cosmological effect, until it makes an analytical graceful exit from this inflationary epoch to a decelerated classical stiff matter expansion phase. The result is $n_s=3$, incompatible with observations.Comment: 10 pages, 2 figures, accepted version to Physical Review D 7

In Pursuit of a Next Generation Network for Public Safety Communications

In the aftermath of Hurricane Katrina, a unitary reliance on Land Mobile Radio systems (LMRs) failed public safety agencies, leaving them without any source of communications once they lost transmission capability. Unfortunately, in the wake of this tragedy, many have dusted off traditional prescriptions for improving public safety communications, such as more dedicated spectrum and more money for single-purpose LMRs (or LMRs based on technology that fails to facilitate broader functionalities). As we explain, however, both the needs underscored by Katrina and the capabilities made possible by emerging technologies call for a different strategy. In this paper, we argue that sound policy favors adoption of a next generation flexible architecture strategy for public safety communications. Such a flexible architecture embraces technological convergence and, accordingly, strives to coordinate existing LMRs, commercial terrestrial services, satellite technology, and wireless broadband systems to provide a robust, reliable, secure, and interoperable broadband communications system. Additionally, this approach would take advantage of multi-mode radios which are already a reality in most segments of the marketplace (except for public safety). Such multi-mode radios are expected to be even more robust once the recently authorized ancillary terrestrial component (ATC) of mobile satellite services becomes an option for public safety agencies. Notably, the flexible architecture that we advocate does not necessarily require additional spectrum dedicated for public safety agencies nor prohibitive financial investment in the equipment needed to use spectrum effectively. Rather, public safety agencies can leverage networks provided by commercial providers - particularly hybrid satellite and terrestrial systems - to satisfy many public safety needs in a cost-effective fashion. To advance this vision, policymakers should ensure that (1) satellite and terrestrial providers are afforded the opportunity - through pro-market and innovative spectrum policies - to develop effective offerings for public safety agencies; and (2) public safety agencies receive sufficient financial support to promote this type of a hybrid, next generation architecture

Spectrum Policy Reform and the Next Frontier of Property Rights

The scarcity of wireless spectrum reflects a costly failure of regulation. In practice, large swaths of spectrum are vastly underused or used for low value activities, but the regulatory system prevents innovative users from gaining access to such spectrum through marketplace transactions. In calling for the propertyzing of swaths of spectrum as a replacement for the current command-and-control system, many scholars have wrongfully assumed the simplicity of how such a regime would work in practice. In short, many scholars suggest that spectrum property rights can easily borrow key principles from trespass law, reasoning that since property rights work well for land, they can work well for spectrum rights as well. But as we explain, spectrum is not the same as land, and a poorly designed property rights regime for spectrum might even be worse than the legacy model of spectrum regulation. This Article addresses three central questions that confront the design and implementation of property rights in spectrum. First, it suggests how policymakers must develop a set of rights and remedies around spectrum property rights that reflect the fact that radio signals defy boundaries and can propagate in unpredictable ways. In particular, if policymakers simply created rights in spectrum and enforced them like rights in land (i.e., with injunctions for trespass), they would invite strategic behavior: spectrum speculators would buy licenses for the sole purpose of suing other licensees when their transmission systems created interference outside the permissible boundary (i.e., act as spectrum trolls). Second, it rejects the suggestion that policymakers establish a unitary property right for spectrum, arguing that policymakers should zone the spectrum by establishing different levels of protection against interference (i.e., an ability to transmit signals with more latitude) in different frequency bands. Finally, this Article discusses what institutional strategy will best facilitate the development of the property right and its enforcement, concluding that an administrative agency - be it a new one or a reformed FCC - is better positioned than a court to develop and enforce the rules governing the use of spectrum so as to facilitate technological progress and prevent parties with antiquated equipment from objecting to more efficient uses of spectrum

Policing the Spectrum Commons

One of the most contested questions in spectrum policy is whether bands of spectrum left as unlicensed will fall victim to the tragedy of the commons. Advocates of increased unlicensed spectrum often downplay what enforcement measures are necessary to minimize interference and to prevent the tragedy of the commons problem. Even imposing spectrum etiquette requirements in addition to the FCC\u27s equipment certification program will fail to address this concern effectively, as the development of such measures - e.g., the requirement that devices listen before they talk - does not ensure that they will be followed. Indeed, if there are incentives for parties to cheat on the rules that prevent tragedy of the commons-type results, some cheaters are likely to emerge and thereby undermine the promise of new and innovative technologies that use unlicensed spectrum. Although the threat posed by cheaters does not undermine completely the commons model of spectrum management, it does underscore that the proponents of that model have focused almost entirely on one half of the issue. To date, these proponents have argued that unlicensed bands can facilitate technological innovation and more efficient uses of spectrum than would a purely private property-like approach. But they have not explained what the FCC should do to prevent deviation from the protocols (or certified equipment) that maximize the effectiveness of shared uses of spectrum. Moreover, tragedy of the commons-type concerns are not merely theoretical ones, as the experience with the citizen\u27s band (CB) radio demonstrated how interference caused by unauthorized uses (such as amplifiers) can undermine a previously popular use of spectrum. In the current environment, technologies like a Wi-Fi Hog, which can take control of and fully exploit a public wi-fi network - or malicious jamming by hackers - pose the same danger. This paper both underscores the need for and develops the analytical framework to guide a new model of spectrum policy for unlicensed bands. In particular, it argues that the FCC should develop a regulatory program that integrates the efforts of end user groups, interested companies, private standard setting bodies, and its own enforcement tools. In one incarnation of this approach, the FCC can ask a private body (such as the IEEE) to report back on its progress in addressing a particular issue - understanding that it may have to pick up where the body left off (either in setting or enforcing the interference mitigation measure). To be sure, we recognize that this spectrum management strategy will require considerable effort to implement, but we believe that a failure to address these issues would be the Achilles\u27 heel of the commons model of spectrum management

Spectrum Policy Reform and the Next Frontier of Property Rights

The scarcity of wireless spectrum reflects a costly failure of regulation. In practice, large swaths of spectrum are vastly underused or used for low value activities, but the regulatory system prevents innovative users from gaining access to such spectrum through marketplace transactions. In calling for the propertyzing of swaths of spectrum as a replacement for the current command-and-control system, many scholars have wrongfully assumed the simplicity of how such a regime would work in practice. In short, many scholars suggest that spectrum property rights can easily borrow key principles from trespass law, reasoning that since property rights work well for land, they can work well for spectrum rights as well. But as we explain, spectrum is not the same as land, and a poorly designed property rights regime for spectrum might even be worse than the legacy model of spectrum regulation. This Article addresses three central questions that confront the design and implementation of property rights in spectrum. First, it suggests how policymakers must develop a set of rights and remedies around spectrum property rights that reflect the fact that radio signals defy boundaries and can propagate in unpredictable ways. In particular, if policymakers simply created rights in spectrum and enforced them like rights in land (i.e., with injunctions for trespass), they would invite strategic behavior: spectrum speculators would buy licenses for the sole purpose of suing other licensees when their transmission systems created interference outside the permissible boundary (i.e., act as spectrum trolls). Second, it rejects the suggestion that policymakers establish a unitary property right for spectrum, arguing that policymakers should zone the spectrum by establishing different levels of protection against interference (i.e., an ability to transmit signals with more latitude) in different frequency bands. Finally, this Article discusses what institutional strategy will best facilitate the development of the property right and its enforcement, concluding that an administrative agency - be it a new one or a reformed FCC - is better positioned than a court to develop and enforce the rules governing the use of spectrum so as to facilitate technological progress and prevent parties with antiquated equipment from objecting to more efficient uses of spectrum