Enforcement in Dynamic Spectrum Access Systems

The spectrum access rights granted by the Federal government to spectrum users come with the expectation of protection from harmful interference. As a consequence of the growth of wireless demand and services of all types, technical progress enabling smart agile radio networks, and on-going spectrum management reform, there is both a need and opportunity to use and share spectrum more intensively and dynamically. A key element of any framework for managing harmful interference is the mechanism for enforcement of those rights. Since the rights to use spectrum and to protection from harmful interference vary by band (licensed/unlicensed, legacy/newly reformed) and type of use/users (primary/secondary, overlay/underlay), it is reasonable to expect that the enforcement mechanisms may need to vary as well.\ud \ud In this paper, we present a taxonomy for evaluating alternative mechanisms for enforcing interference protection for spectrum usage rights, with special attention to the potential changes that may be expected from wider deployment of Dynamic Spectrum Access (DSA) systems. Our exploration of how the design of the enforcement regime interacts with and influences the incentives of radio operators under different rights regimes and market scenarios is intended to assist in refining thinking about appropriate access rights regimes and how best to incentivize investment and growth in more efficient and valuable uses of the radio frequency spectrum

Managing Shared Access to a Spectrum Commons

The open access, unlicensed or spectrum commons approach to managing shared access to RF spectrum offers many attractive benefits, especially when implemented in conjunction with and as a complement to a regime of marketbased, flexible use, tradable licensed spectrum ([Benkler02], [Lehr04], [Werbach03]). However, as a number of critics have pointed out, implementing the unlicensed model poses difficult challenges that have not been well-addressed yet by commons advocates ([Benjam03], [Faulhab05], [Goodman04], [Hazlett01]). A successful spectrum commons will not be unregulated, but it also need not be command & control by another name. This paper seeks to address some of the implementation challenges associated with managing a spectrum commons. We focus on the minimal set of features that we believe a suitable management protocol, etiquette, or framework for a spectrum commons will need to incorporate. This includes: (1) No transmit only devices; (2) Power restrictions; (3) Common channel signaling; (4) Mechanism for handling congestion and allocating resources among users/uses in times of congestion; (5) Mechanism to support enforcement (e.g., established procedures to verify protocol is in conformance); (6) Mechanism to support reversibility of policy; and (7) Protection for privacy and security. We explain why each is necessary, examine their implications for current policy, and suggest ways in which they might be implemented. We present a framework that suggests a set of design principles for the protocols that will govern a successful commons management regime. Our design rules lead us to conclude that the appropriate Protocols for a Commons will need to be more liquid ([Reed05]) than in the past: (1) Marketbased instead of C&C; (2) Decentralized/distributed; and, (3) Adaptive and flexible (Anonymous, distributed, decentralized, and locally responsive)

Coordinated Dynamic Spectrum Management of LTE-U and Wi-Fi Networks

This paper investigates the co-existence of Wi-Fi and LTE in emerging unlicensed frequency bands which are intended to accommodate multiple radio access technologies. Wi-Fi and LTE are the two most prominent access technologies being deployed today, motivating further study of the inter-system interference arising in such shared spectrum scenarios as well as possible techniques for enabling improved co-existence. An analytical model for evaluating the baseline performance of co-existing Wi-Fi and LTE is developed and used to obtain baseline performance measures. The results show that both Wi-Fi and LTE networks cause significant interference to each other and that the degradation is dependent on a number of factors such as power levels and physical topology. The model-based results are partially validated via experimental evaluations using USRP based SDR platforms on the ORBIT testbed. Further, inter-network coordination with logically centralized radio resource management across Wi-Fi and LTE systems is proposed as a possible solution for improved co-existence. Numerical results are presented showing significant gains in both Wi-Fi and LTE performance with the proposed inter-network coordination approach.Comment: Accepted paper at IEEE DySPAN 201

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

Dimensions of cooperative spectrum sharing: Rights and enforcement

Sharing of radio spectrum requires a careful and nuanced understanding of the rights of incumbents and spectrum entrants. In addition, the dynamics of stakeholders can be understood by examining how various rights are arranged (and rearranged) among them. Importantly, understanding the rights and their distribution is the predicate to developing rational and useful enforcement approaches. In this paper, we show that spectrum sharing involves a rearrangement of the rights associated with radio spectrum among stakeholders. We show how this rearrangement of rights implies the definition of new bundles of rights, appropriate to each particular sharing scenario. We discover these rights - and their (re)arrangement - by examining several cases of spectrum use. We begin with the rights associated with exclusive use and proceed to consider rights arrangement in commons and different spectrum sharing configurations. Further, in the case of commons, we explicitly examine how governance of commons can affect the rights distribution in spectrum. In each case, the bundles of rights associated with each stakeholder changes. New bundles of rights have consequences, not only on the behavior of spectrum users but also on the enforcement process. Our examination of the bundles of rights shows that each rearrangement results in different approaches to enforcement. We demonstrate this by revisiting enforcement in the cases we examine. © 2014 IEEE

Cross Layer Aware Adaptive MAC based on Knowledge Based Reasoning for Cognitive Radio Computer Networks

In this paper we are proposing a new concept in MAC layer protocol design for Cognitive radio by combining information held by physical layer and MAC layer with analytical engine based on knowledge based reasoning approach. In the proposed system a cross layer information regarding signal to interference and noise ratio (SINR) and received power are analyzed with help of knowledge based reasoning system to determine minimum power to transmit and size of contention window, to minimize backoff, collision, save power and drop packets. The performance analysis of the proposed protocol indicates improvement in power saving, lowering backoff and significant decrease in number of drop packets. The simulation environment was implement using OMNET++ discrete simulation tool with Mobilty framework and MiXiM simulation library.Comment: 8 page

LTE AND WIFI CO-EXISTENCE IN 5 GHZ UNLICENSED BAND

Since the future mobile networks will require significantly higher data throughput, and the Long-Term Evolution (LTE) licensed bands are already occupied, the frequency band extension and the data rate increase may be achieved by using some of the available unlicensed bands. The most appropriate unlicensed band for this purpose lies in 5 GHz frequency range. However, this unlicensed band is already occupied by WiFi networks and a special attention has to be paid to coordinate these two different networks in the shared spectrum usage. Therefore, this paper considers the shared access co-existence in 5 GHz unlicensed band between uncoordinated LTE and WiFi networks. More precisely, it considers the influence of the LTE downlink transmission on the performance of the WiFi networks. The experimental results show that the LTE significantly degrades the WiFi network performance, which means that some of the coordination algorithms have to be employed