Efficient Spectrum Management Research Articles

Cognitive (LabVIEW) on FPGA–a novel approach for dynamic spectrum sensing

The spectrum allotted for communications has been distributed to various service providers, who maintain and manage their portion of the spectrum by accommodating as many users as possible through spectral management techniques. Static spectrum management has been replaced by dynamic spectrum management to meet the vastly increasing number of users. Although dynamic spectrum management techniques have enabled the efficient assignment of channels to the user, it has been statistically observed that a huge part of the communications spectrum is scarcely used at all times. Cognitive radio is a useful tool for efficient dynamic spectrum management. The cognitive radio is adaptive in nature and is most effective because of its ability to monitor the spectrum, sense the channel occupancy and mobilise the secondary user to an unused primary user channel, as well as to relocate the secondary user if the primary user wishes to communicate. In this work, the energy-detection method and the cyclostationary method, which are the methods to sense the spectrum, are analysed and the results are compared. Simulation is done using a LabVIEW tool (National Instruments, Bangalore, India) and finally the implementation is done on a Field Programmable Gate Array.

Right-Sizing Spectrum Auction Licenses: The Case for Smaller Geographic License Areas in the TV Broadcast Incentive Auction

Right-Sizing Spectrum Auction Licenses: The Case for Smaller Geographic License Areas in the TV Broadcast Incentive Auction

Performance Evaluation of Secondary Users Operating on a Heterogeneous Spectrum Environment

Radio spectrum is a limited natural resource and with the increasing number of wireless devices, an efficient spectrum management concept to make a better utilization of this resource is essential....

Cooperative bargaining solution for efficient and fair spectrum management in cognitive wireless networks

SUMMARYThis paper studies the fairness among the primary users (PUs) and the secondary users (SUs) for resource allocation in cognitive radio systems. We propose a novel co‐opetition strategy based on the Kalai–Smorodinsky bargaining solution to balance the system efficiency and the fairness among users. The strategy formulates the spectrum sharing problem as a nonlinear and integral sum utility maximization subject to a set of constraints describing the co‐opetition among the PUs and the SUs. Then, we solve the maximization problem by proposing a heuristical method that consists of four steps: multi‐PU competition, PU's subcarrier contribution, multi‐SU competition, and SU's subcarrier contribution. Extensive simulation results are presented by comparing the co‐opetition strategy with several conventional ones, including the Kalai–Smorodinsky bargaining solution, sum rate maximization as well as the Max–Min. Results indicate that the co‐opetition strategy can jointly balance the system efficiency and fairness in multiuser resource allocation, as it is able to support more satisfied users and in the meanwhile improve the utility of those unsatisfied. Moreover, the co‐opetition can help enable the coexistence of the PUs and the SUs in cognitive radio systems. Copyright © 2013 John Wiley & Sons, Ltd.

The Economics of Spectrum Sharing

In light of the growing demand for wireless broadband spectrum, significant attention is now being devoted to more effectively utilizing federal allocations of spectrum, either by entirely repurposing for commercial use or sharing with commercial users. Spectrum sharing is believed to be one way to allow commercial users to access a band without incurring the costs of completely clearing existing federal users. While sharing avoids costs of clearing federal users, spectrum sharing has its own costs and is likely to impact the value of the shared spectrum. The purpose of this paper is to understand the economic tradeoffs associated with various spectrum sharing arrangements.This paper will begin with a brief description of current policy issues around sharing and review potential frameworks for making spectrum allocation decisions. We posit that efficient spectrum allocation decisions should maximize the likelihood of achieving the policymakers’ goals. Moreover, whatever the goals of policymakers, economically efficient use of spectrum creates value for achieving those goals. Consequently, efficient spectrum use should only be sacrificed for explicit policy objectives that are considered more valuable than the forgone value of using the spectrum efficiently. In trying to achieve efficient spectrum management, or in evaluating proposed departures from efficient use of spectrum, it is crucial to know the costs and forgone opportunity associated with any allocation policy. This is especially true when evaluating spectrum sharing proposals, because any specific proposal inevitably involves a trade-off between costs and benefits of two or more competing users.To understand this tradeoff we will discuss the theoretical drivers of commercial spectrum value. The value of spectrum is essentially derived from the inherent profitability of wireless services deployed on the spectrum. In the case of shared spectrum, the total value of the spectrum is the sum of the value to each shared use. To the extent that sharing restricts the operations or increases the costs of deployment for a given user, it diminishes that users profitability. Only if the sharing arrangement increases the value to another user by a greater amount will the total value of the uses of a band of spectrum increase. Based on these principles of spectrum value, the next section will discuss how spectrum sharing will likely impact the value of spectrum to a single user and the cumulative value to all users. If the total value of the spectrum for all shared uses is less than the value for a single user, then spectrum sharing diminishes the potential value of the spectrum; likewise, when the total shared value is higher than the single user value, sharing increases the spectrum value. We will explore mechanisms through which various types of spectrum sharing might impact the value of a single user, and the resulting cumulative value of the band to all users. We will use illustrative examples to illustrate this impact of sharing. Likely examples include the geographic sharing proposed by NTIA for the 1675-1710 MHz band, the FCC’s proposed small cell sharing in the 3.5 GHz band, and the sharing between TV Broadcasters and unlicensed users in the TV white spaces. While geographic sharing of the 1675-1710 MHz band could limit costs to federal reallocation, it would also diminish the economic value of the spectrum by eliminating revenues in the exclusion zones, reducing any nationwide premium on the spectrum, and potentially increasing costs to deploying wireless broadband services. To evaluate the relative value of sharing proposals in the 3.5 GHz and TV Broadcast bands, we must compare the total potential value from all shared users to the value that a single commercial user could derive from this spectrum.

Enforcement and Spectrum Sharing: Case Studies of Federal-Commercial Sharing

To promote economic growth and unleash the potential of wireless broadband, there is a need to introduce more spectrally efficient technologies and spectrum management regimes. That led to an environment where commercial wireless broadband need to share spectrum with the federal and non-federal operations. Implementing sharing regimes on a non-opportunistic basis means that sharing agreements must be implemented. To have meaning, those agreements must be enforceable. With the significant exception of license-free wireless systems, commercial wireless services are based on exclusive use. With the policy change facilitating spectrum sharing, it becomes necessary to consider how sharing might take place in practice. Beyond the technical aspects of sharing, that must be resolved lie questions about how usage rights are appropriately determined and enforced. This paper is reasoning about enforcement in a particular spectrum bands (1695-1710 MHz and 3.5 GHz) that are currently being proposed for sharing between commercial services and incumbent spectrum users in the US. We examine three enforcement approaches, exclusion zones, protection zones and pure ex post and consider their implications in terms of cost elements, opportunity cost, and their adaptability.

Design and Experimental Validation of a GMPLS/PCE Control Plane for Elastic CO-OFDM Optical Networks

ITU-T Recommendation G.694.1 defines normative DWDM frequency grids, each being a reference set of values that correspond to allowed nominal central frequencies, obtained using a fixed channel spacing (e.g., 12.5 GHz, 25 GHz, 50 GHz or 100 GHz). This rigid, grid-based approach does not seem well adapted for data rates beyond 100 Gb/s, is particularly inefficient when a whole wavelength is assigned to a lower rate optical path, and is not flexible enough for multi-rate systems . Consequently, the next generation of optical networks will require a flexible, highly efficient and adaptive management of the optical spectrum, along with advanced optical modulation schemes that efficiently use allocated spectrum slots, and recent progress on optical network technology justifies research on both new optical transmission systems as well as the applicability of control and management frameworks to such networks. We design and deploy a GMPLS control plane for flexible optical networks with coherent optical orthogonal frequency-division multiplexing (O-OFDM) transmission; we detail its functional architecture, which combines a centralized entity that performs path routing and modulation assignment, with a distributed spectrum allocation. The centralized entity (i.e., a path computation element) uses pre-configured static path characterizations, based on exhaustive OFDM transmission simulations, when performing dynamic path computation in line with GMPLS constrained shortest path mechanisms. The distributed spectrum allocation assigns frequency ranges (slots) to connection requests, by using dynamic signaling procedures and applying slot assignment policies. We summarize the control plane protocol extensions involved in the main functional aspects: routing and topology dissemination, path computation, signaling and resource reservation. We experimentally validate and evaluate the integrated centralized PCE and GMPLS control plane in a control plane testbed, obtaining key performance indicators such as path setup latency and blocking probability for different frequency slot assignment policies.

Increasing Spatial Spectrum Utilization Through Opportunistic User-to-User Communications

The requirements for ubiquitous and highly reliable wireless services, combined with the low utilization of licensed spectrum, call for flexible and efficient spectrum management schemes. To this end, a lot of attention is paid in the literature on allowing secondary-external users to opportunistically access the licensed spectrum. In parallel to these efforts, the question is whether the licensed users could further improve their own spectrum utilization. In this paper, we focus on increasing the spatial spectrum utilization of an infrastructure-based wireless system by adding autonomous functionality to the primary (system) users. An opportunistic operation mode for the uplink (UL) period, totally transparent to the base station (BS) of the system, is introduced. Users operating in this mode identify spatial spectrum UL opportunities by interpreting BS broadcast messages, and exploit these opportunities by establishing direct connections. It is shown that multiple direct connections can take place in parallel with a single standard UL transmission. Moreover, significant additional throughput is achieved, and in most of the cases, the energy consumption for the direct connections is lower than that of the conventional ones (using the standard mode).

India: Case Study on the Supreme Court Ruling on the 2G Spectrum Scam

In 2008, the Central Government of India granted 122 telecom licenses to various companies in response to 575 applications for licenses. In a report in 2010-11, the Comptroller and Auditor General (CAG) of India concluded that the allocation of these 122 licenses was characterised by policy gaps and irregularities in procedure. The Government was criticised for cherry-picking the telecom regulators recommendations; for ignoring market based mechanisms like auctions; and for administratively allocating licenses at prices discovered in 2001 on the pretext of providing a level playing field with incumbent operators. The estimated loss by the CAG according to three different estimates ranged from Rs 53523 to 139652 crores. Media coverage of the report and license allocation, hyped as the “2G Scam,” was followed by public outrage and protests. On the 2nd of February 2012, the Supreme Court of India, in response to a Public Interest Litigation (PIL), cancelled all 122 telecom licenses granted in 2008 and directed that the spectrum linked with these licenses be auctioned.The verdict took the telecom industry by surprise and left the Government running for cover. The unaffected incumbent operators praised the verdict for giving a blank slate to the Government - an opportunity to chalk out a fresh concrete policy for efficient management of spectrum and maximization of government revenues. The affected licensees, however, complained that the Supreme Court left a question mark with respect to the future of operators who had already rolled out their networks. Many investors such as the Telenor Group (of Uninor) had already invested over Rs 6,100 crores in equity and over Rs 8,000 crores in corporate guarantees as a foreign investor that trusted a telecom licence stamped by the Government of India. The company had appealed to the government for a solution so that its customers are not affected by the verdict. ''We also expect the authorities to ensure that our 36 million customers, 17500 workforce and 22000 partners are not unjustly affected,'' said Uninor . A few other foreign investors even threatened to invoke foreign investment treaties to indemnify their losses. Some others have decided to write off the losses and exit the market completely.Industry experts fear that the reduced competition by the mass cancellation of licenses is expected to lead to an increase in tariffs in the near future. Further, experts also fear that a few telecom infrastructure companies are expected to become unsustainable as their primary customers were the cancelled licensees. The Supreme Court ruling comes in a scenario wherein telecommunications in India is torn between the New Telecom Policy of 1999 (NTP 1999) and the Draft New Telecom Policy of 2011 (DNTP 2011), which is yet to be finalised and notified in February 2012. In these times of uncertainty, all stakeholders look towards the Central Government for guidance with very high expectations.

Dynamic Spectrum Auction and Load Balancing Algorithm in Heterogeneous Network

Mobile communication plays an important role in the future of communication systems. To meet personalized and intelligent requirements, mobile communication has evolved from single wireless cellular network to heterogeneous mobile communication network, including wireless cellular network, wireless local network, and wireless personal network. In the heterogeneous communication system, to entirely fulfill the spectrum resource complementary advantages of such a heterogeneous wireless network, the spectrum resource trade algorithm has attracted tremendous research efforts. In this paper, the advantages and disadvantages of dynamic spectrum allocation and load balancing are discussed and spectrum auction takes the place of spectrum allocation to maximize the operation revenue. The authors design a joint spectrum auction and load balancing algorithm (SALB) based on heterogeneous network environment to develop a more flexible and efficient spectrum management. The simulation result shows that SALB increases the operation profit significantly.

Allocative vs. technical spectrum efficiency

Achieving allocative and technically efficient spectrum management is a key aspect of deregulatory reforms in several OECD countries. However, reform legislation offers few clues as to how these objectives should rank when they conflict with one another. An ‘innocent’ prior acquisition of service-neutral spectrum at an efficiently run auction may prove allocative efficient but fail to be technically efficient if the spectrum is left fallow in the short term. Accountability for the productive usage of a public resource and pressures from short-term political cycles may induce regulators to mandate some minimal level of activity. Two plausible regulatory responses are considered: use it or lose it clauses and spectrum trading incentives. The former favours technical efficiency whilst the latter promotes allocative efficiency. The argument is formalised in a simple economic model buttressing the roles of uncertainty and transaction costs to assert the primacy of allocative efficiency over technical efficiency.

Docitive networks: an emerging paradigm for dynamic spectrum management [Dynamic Spectrum Management

Prime design goals for next-generation wireless networks to support emerging applications are spectral efficiency and low operational cost. Among a gamut of technical solutions, cognitive approaches have long been perceived as a catalyst for the above goals by facilitating the coexistence of primary and secondary users by means of efficient dynamic spectrum management. While most available techniques today are essentially opportunistic in nature, a truly cognitive device needs to exhibit a certain degree of intelligence to draw optimum decisions based on prior observations and anticipated actions. Said intelligence however, comes along with high complexity and poor convergence, which currently prevents any viable deployment of cognitive networks. We thus introduce an emerging and largely unexplored concept of docitive networks, where nodes effectively teach other nodes with the prime aims of reducing cognitive complexity, speeding up the learning process, and drawing better and more reliable decisions. To this end, we review some important concepts borrowed from the machine learning community for both centralized and decentralized systems, in order to position the emerging docitive with known cognitive approaches. Finally, we validate introduced concepts in the context of a primary digital television system dynamically coexisting with IEEE 802.22 secondary networks. For this scenario, we demonstrate the superiority of various unprecedented docitive over known opportunistic/cognitive algorithms.

Minding the gap(s) in Australian spectrum law

Achieving efficient spectrum management in the pursuit of the public interest was a key aspect of the legislative reforms enacted through the Radiocommunications Act 1992. However, the Act is unclear about the precise nature of the efficiencies to achieve and choices between different efficiency objectives are often dictated by the nature of the services, bands and market considered. This article argues that efficient spectrum policy can be furthered by crafting additional licensing regimes or expanding the possibilities of existing regimes. Despite successes in moving towards this goal, some legal rules still feed a pool of licensing gaps that detract from the public interest they are meant to serve. The article discusses remedies to these gaps. Copyright 2010 Benoit Pierre Freyens. No part of this article may be reproduced by any means without the written consent of the publisher.

A mixed spectrum management framework for the future wireless service based on techno-economic analysis: The Korean spectrum policy study

The evolution of radio technology and various services has increased the world's dependence on wireless communications. The demand for and value of spectrum resources therefore are also increasing. Spectrum efficiency is the most important factor in managing spectrum scarcity. However, under the current spectrum management approach, it is difficult to adopt innovative technologies that improve spectrum efficiency and flexible usage in the current dynamic wireless market. Recently, there have been several approaches to improve efficient use of spectrum resources, and each approach has its own advantages and disadvantages. Therefore, this research first discusses current issues and analyzes relative social welfare based on the different characteristics of technology and market conditions to compare various attributes of each approach. Based on the techno-economic simulation results, this paper introduces a mixed spectrum management framework for the future wireless service and support policy makers’ decision making. Furthermore, the mixed spectrum policy to spectrum management in Korea is proposed to find a more realistic and efficient spectrum management policy.

Performance evaluation of advanced spectrum functionalities for future radio networks

AbstractThis paper presents novel spectral resource management (SRM) functionalities of WINNER ‡The WINNER project is a major European research activity to develop a flexible and scalable radio access interface for future wireless communication systems. project. The proposed SRM spectrum architecture uses more efficient resource allocation techniques where flexible spectrum access and usage leads to more capable and faster services with high quality‐of‐service (QoS) giving more user satisfaction than conventional networks. In this context, short‐term (ST) spectrum assignment is proposed where spectral resources are exchanged between WINNER radio access networks (RANs) on a fast basis, leading to a better utilization of the spectrum. Moreover, multi‐band scheduler (MBS) and base station (BS) to BS communications are presented as key enablers for efficient dynamic spectrum management. Performance gains of ST spectrum assignment are analyzed in a multi‐network, multi‐cell environment based on realistic traffic patterns while taking inter‐cell interference into account. The results confirm that spectrum availability and utilization can be considerably enhanced. Copyright © 2008 John Wiley & Sons, Ltd.

HC-MAC: A Hardware-Constrained Cognitive MAC for Efficient Spectrum Management

Radio spectrum resource is of fundamental importance for wireless communication. Recent reports show that most available spectrum has been allocated. While some of the spectrum bands (e.g., unlicensed band, GSM band) have seen increasingly crowded usage, most of the other spectrum resources are underutilized. This drives the emergence of open spectrum and dynamic spectrum access concepts, which allow unlicensed users equipped with cognitive radios to opportunistically access the spectrum not used by primary users. Cognitive radio has many advanced features, such as agilely sensing the existence of primary users and utilizing multiple spectrum bands simultaneously. However, in practice such capabilities are constrained by hardware cost. In this paper, we discuss how to conduct efficient spectrum management in ad hoc cognitive radio networks while taking the hardware constraints (e.g., single radio, partial spectrum sensing and spectrum aggregation limit) into consideration. A hardware-constrained cognitive MAC, HC-MAC, is proposed to conduct efficient spectrum sensing and spectrum access decision. We identify the issue of optimal spectrum sensing decision for a single secondary transmission pair, and formulate it as an optimal stopping problem. A decentralized MAC protocol is then proposed for the ad hoc cognitive radio networks. Simulation results are presented to demonstrate the effectiveness of our proposed protocol.

Efficient Design of OFDMA-Based Programmable Wireless Radios

With the increasing demand for efficient spectrum management, programmable wireless radios can potentially play a key role in shaping our future spectrum use. In this paper, we consider the design of low-power programmable wireless radios based on orthogonal frequency division multiple access (OFDMA). To meet the demands of higher data rate communications, we split OFDMA symbols carrying multiuser data across several noncontiguous bands of available spectrum. To relax power consumption in analog-to-digital and digital-to-analog converters, we use a programmable narrowband RF front end comprising of programmable synthesizers and fixed low-pass filters. To perform digital baseband signal processing in an energy efficient manner, we propose efficient designs for the fast Fourier transform (FFT) and inverse FFT (IFFT) modules. Our designs of the FFT/IFFT modules reduce power consumption and chip area, and are capable of handling the dynamic nature of spectrum in programmable radios. To recover data that falls within the transition band of the filters, we propose a combiner similar to maximal ratio combiner. We also present the complete design of programmable wireless radios in accordance with the IEEE 802.22 (draft) standard.

Improving Public Safety Communications: An Analysis of Alternative Approaches

There is a broad consensus that the communication capabilities of America’s public safety agencies need to be improved. Public safety communications systems are not interoperable, making it difficult for agencies to communicate with one another. Moreover, these systems generally do not provide the broadband capabilities that are increasingly commonplace in commercial cell phones. In December 2006, the FCC proposed a “national, centralized approach to maximize public safety access to interoperable, broadband spectrum.” The FCC plan aimed to ensure efficient and effective use of the spectrum provided to public safety, while promoting “the deployment of advanced broadband applications, related radio technologies, and modern, IP-based architectures.” In 2007, a company called Cyren Call proposed allocating of an additional 30 MHz of spectrum to construct a nationwide broadband network which would be used for both commercial and public safety purposes. This paper presents our analysis of the Cyren Call proposal. We find that the plan suffers from serious flaws, and that its adoption would not result in more effective communications solutions for public safety. In addition, we find that sufficient spectrum has already been allocated for public safety use, and that more efficient spectrum management and the adoption of modern wireless technology can provide the interoperability and advanced capabilities public safety agencies need.

A performance evaluation of distributed dynamic channel allocation protocols for mobile networks

AbstractTechnological advances coupled with the proliferation of wireless devices among mobile users require efficient resource management and reuse of the scare radio spectrum allocated to wireless and mobile communication systems. Several channel allocation protocols based on a mutual exclusion paradigm have been developed. However, very little data have been reported to compare these protocols. In this paper, we review four of the best known distributed dynamic channel and resource allocation algorithms based on the mutual exclusion paradigm. While the first three channel alloctaion protocols (Cao et al., Choy et al. and Prakash et al.) are based on the co‐channel interference, the fourth protocol, which is known as DDRA, adopts the co‐group interference approach. We present an extensive set of simulation experiments to evaluate and compare the performance of these four protocols using realistic scenarios. Our results indicate clearly that DDRA algorithm has shown the shortest response time and highest blocking rate among all of the four channel allocation protocols. Cao et al. algorithm exhibits a better blocking rate when compared to the three other schemes. This is due to the fact that it reuses communication channels optimally. Last, but not least, we discuss the basic fault tolerant machanisms that can be used to enhance further these protocols while dealing with the base stations, mobile hosts, or links' failure. Copyright © 2006 John Wiley & Sons, Ltd.

Spatial‐temporal statistics of rainrate random fields

Rainrate near the ground can be interpreted as a collection of random variables forming a random field parameterized by three coordinates: two spatial coordinates and one temporal. Interest among the radio propagation community has been focused on the first order statistics of these random variables, principally on the average annual probability distribution of rainrate as a function of location. However, increasingly interest is turning to second order statistics describing high‐resolution rainrate variation in both time and space. This information is important for the design of fade countermeasures and for efficient spectrum management. In this paper radar data from a widespread, slow moving and intense, stratiform rain event experienced by the southeastern UK on May 1, 2001, are used to calculate the second order, spectral, statistics of spatial‐temporal log rainrate variation. It is demonstrated that log rainrate is self‐similar in all three coordinates and that symmetry exists between the spatial and temporal variation. These data are used to develop an isotropic, spatial‐temporal log rainrate model assuming that log rainrate is a homogeneous, Gaussian, random field. This model is developed further to yield closed form expressions for the mean and covariance of the random fields associated with rainrate, with specific attenuation and the logarithm of specific attenuation. Furthermore, expressions for the temporal covariance of the rain attenuation experienced by pairs of radio links are developed, and these expressions are tested against measured rain attenuation data from an experimental link.