Incumbent Users Research Articles

The tragedy of the commons: the logic of entry and the dynamic process under two scenarios

This paper analyzes the dynamics of entry and adjustment that underlies the process leading to the tragedy of the commons under two scenarios, one in which the users only react ex post to the entry of other users and the other in which the users anticipate and proact to such entry. The key to our analysis is the logic of entry based on the devaluation cost, which explains (1) why entry takes place when the incumbent users are in temporary equilibrium, (2) how this equilibrium shifts sequentially with the entry of new users, (3) why such equilibria resemble either the Cournot-Nash equilibrium of a static game or the Stackelberg type equilibrium of a dynamic game depending on the reactive or the proactive nature of the users, (4) why the stocks owned by the users in the proactive case depend on the order of entry and remain unchanged once determined at the point of entry. The speed of depletion, cumulative profits of the users, and the distribution pattern of the ownership differ significantly between the two scenarios. Our theory also explains why and how duopoly and oligopoly emerge through the process of entry and adjustment and acquire different equilibrium features.

Coexistence of 5G With the Incumbents in the 28 and 70 GHz Bands

A promising way of realizing the fifth generation (5G) wireless systems is to operate 5G deployments at higher frequency bands, specifically in the millimeter-wave (mmW) spectrum (30-300 GHz). Access to such spectrum bands will enable future 5G wireless systems to meet the 5G requirements of peak rate greater than 10 Gb/s, and cell edge rate of up to 1 Gb/s. However, the emerging 5G systems will need to coexist with a number of incumbent systems in these bands. This paper provides an extensive study of the co-channel coexistence of 5G in two critical mmW bands, 27.5-28.35 GHz (28 GHz) and 71-76 GHz (70 GHz) bands, where fixed satellite service (FSS) and fixed service (FS), such as wireless backhaul, are the predominant incumbent users. In the 28-GHz study, we show that interference from 5G into the FSS space stations can be kept below the FSS interference protection criterion. We also characterize the minimum separation distance between the FSS earth stations (ESs) and 5G in order to protect the 5G system from interference due to the ESs transmissions. In the 70-GHz study, we show that the 5G-to-FS interference could be a potential issue in certain scenarios, but we introduce techniques to significantly suppress this interference, while maintaining acceptable performance of the 5G systems. For each study, we suggest appropriate deployment strategies for a 5G system based on our results.

Optimal Cognitive Access and Packet Selection Under a Primary ARQ Process via Chain Decoding

This paper introduces a novel technique that enables access by a cognitive secondary user (SU) to a spectrum occupied by an incumbent primary user (PU) that employs Type-I hybrid automatic retransmission request (ARQ). The technique allows the SU to perform selective retransmissions of SU data packets, whose transmission previously failed. The temporal redundancy introduced by the PU ARQ protocol and by the selective retransmission process of the SU can be exploited by the SU receiver to perform interference cancellation (IC) over multiple transmission slots, thus creating a “clean” channel for the decoding of the concurrent SU or PU packets. The chain decoding (CD) technique is initiated by a successful decoding operation of an SU or a PU packet and proceeds by an iterative application of IC as previously buffered packets become decodable and their interference can be removed, thus making it possible to recover the concurrent data packets, and so on, until no more packets are decodable. Based on this scheme, an optimal policy is designed that maximizes the SU throughput under a constraint on the average long-term PU performance. The optimality of the CD protocol is proved, which determines which packet the SU should send at any given time, based on four basic rules. Moreover, a decoupling principle is proved, which establishes the optimality of decoupling the secondary access strategy from the CD protocol. Specifically, first , the SU access policy, optimized via dynamic programming, specifies whether the SU should access the channel or remain idle, based on a compact state representation of the protocol, and second , the CD protocol embeds four basic rules that are used to select the packet transmitted by the SU. It is shown numerically that CD outperforms by up to 35% other schemes considered in the literature, which do not employ retransmissions at the SU pair and thus do not exploit the full potentiality of IC.

Licensed-Assisted Access for LTE in Unlicensed Spectrum: A MAC Protocol Design

Licensed-assisted access (LAA), which conveys data information via both licensed and unlicensed bands through spectrum aggregation, becomes a promising solution to enhance the capacity of wireless systems. In view of the potential impact on the incumbent system operating in unlicensed bands, the medium access control (MAC) protocol design for LAA system to harmonically coexist with its neighboring incumbent users is one of the most critical and challenging issues. In this paper, we consider a long-term evolution-based LAA (LAA-LTE) system operating in the WiFi unlicensed spectrum, for which the listen-before-talk-based MAC protocol is carefully designed. By quantifying the WiFi throughput and packet delay in the coexisting system, we formulate the constraints of LAA-LTE transmission time to fairly maintain WiFi services. The conditions of known and unknown network size of incumbent WiFi system are each considered separately. Then, the feasible region of LAA-LTE transmission time is determined, and the LAA-LTE protocol is optimized for maximizing the LAA-LTE throughput or the overall throughput contributed by both LAA-LTE and WiFi system. The theoretical analysis is validated via simulation, which also illustrates important observations when LAA-LTE and WiFi systems coexist. This paper offers guidelines to design the LAA-LTE system, paving the way to a controllable, not only harmonious, coexistence of LAA-LTE and WiFi systems in the unlicensed spectrum.

MM-Wave Planner Antenna For Wireless Communication

The expectation of end users for and data allowance puts pressure on network operators in meeting demand and leads to requests from operators for access to greater amounts of spectrum. Making spectrum available to meet the future requirements of mobile broad band services is complex as prime spectrum for mobile broadband services is also access to services exhibiting increased speed heavily utilised by other services and is a scarce resource. Communications regulators must consider the impact on existing spectrum management arrangements and incumbent users. When making further spectrum available. Some of the issues to be taken into account , 1. Determining when the effect of making spectrum available for mobile broadband services is no longer the highest value use as this may preclude other uses of the spectrum with inherent public benefit. 2. Considering whether greater spectral efficiency can be achieved by network operators in existing spectrum holdings. 3. Considering whether the needs of incumbent users of spectrum can be balanced with the future spectrum requirements for mobile broadband services. The global bandwidth shortage facing wireless carriers has motivated the exploration of the underutilized millimeter wave (mm- wave) frequency spectrum for future broadband cellular communication networks. There is, however, little knowledge about cellular mm wave propagation in densely populated indoor and outdoor environments. Obtaining this information is vital for the design and operation of future fth generation cellular networks that use the mm-wave spectrum. In this paper, we present the motivation for new mm -wave cellular systems, methodology, and hardware for measurements and offer a variety of measurement results that show 28 and 38 GHz frequencies can be used when employing steerable directional antennas at base stations and mobile devices. Keywords—CPW, aperture coupled slot, frequency, spectrum, mm wave technology.

A proposed enhanced scheme for the dynamic frequency hopping performance in the IEEE 802.22 standard

AbstractThis paper presents an integrated scheme for the dynamic‐frequency‐hopping (DFH) technique provided in literature for the IEEE 802.22 standard supporting wireless regional area networks (WRANs). The performance of DFH is analyzed thoroughly for various channel models and for a multiple‐input multiple‐output systems. The core of this research is based on the coexistence of digital terrestrial TV broadcasting and the WRANs in the TV white space. The proposed technique aims at protecting the incumbent users from interfering with the cognitive broadband access in the TV spectrum. In order to achieve this, spectrum sensing is performed in the intended working channel in DFH while spectrum monitoring with an energy‐ratio (ER) algorithm is applied during the WRAN data transmission in the working channel. Hence, in the DFH‐ER algorithm, the reappearance of a digital terrestrial TV signal in a band occupied by the WRANs would be detected immediately. This will provide interference free performance for the licensed signal as well as reliable data transmission for the unlicensed ones. Both analyses and simulation results of the proposed DFH‐ER technique compared with the conventional DFH scenario exemplify the enhancement of the WRAN data transmission while protecting the digital terrestrial TV users. Copyright © 2016 John Wiley & Sons, Ltd.

Protection of Incumbent Services and Its Impact on Coverage of TV Band Device Networks in TV White Space

This paper presents a set of candidate regulatory requirements for TV band devices (TVBDs) in the Rep. of Korea. To guarantee the protection of incumbent services, especially digital TV (DTV) and wireless microphones, in TV frequency bands, we suggest minimum separation distances of TVBDs from the noise-limited contour according to incumbent users and TVBD types. This paper also deals with multiple sets of separation distances of a co-channel TVBD network from a DTV protected contour on the basis of the radio propagation characteristics of different geographic areas to make good use of TV white space (TVWS) and safely protect the DTV service. We present a low-power transmission mode of TVBDs and the relevant separation distances for small-cell deployment. The service coverage reduction ratio of a TVBD network is investigated in the presence of DTV interference in four geographic areas. The TVWS field verification results, conducted on the island of Jeju (Rep. of Korea), show that incumbent services operate well without harmful interference from neighboring TVBDs with the proposed separation distances.

<formula> <tex>$P^{2}$</tex> </formula>-SAS: Privacy-Preserving Centralized Dynamic Spectrum Access System

Centralized spectrum management is one of the key dynamic spectrum access (DSA) mechanisms proposed to govern the spectrum sharing between government incumbent users (IUs) and commercial secondary users (SUs). In the current centralized DSA designs, the operation data of both government IUs and commercial SUs need to be shared with a central server. However, the operation data of government IUs are often classified information and the SU operation data may also be commercial secrets. The current system design dissatisfies the privacy requirement of both IUs and SUs, since the central server is not necessarily trustworthy for holding such sensitive operation data. To address the privacy issue, this paper presents a privacy-preserving centralized DSA system ( $P^{2}$ -SAS), which realizes the complex spectrum allocation process of DSA through efficient secure multi-party computation. In $P^{2}$ -SAS, none of the IU or SU operation data would be exposed to any snooping party, including the central server itself. We formally prove the correctness and privacy-preserving property of $P^{2}$ -SAS and evaluate its scalability and practicality using experiments based on real-world data. Experiment results show that $P^{2}$ -SAS can respond an SU’s spectrum request in 6.96 s with communication overhead of less than 4 MB.

Distributional Effects of the Transition to Property Rights for a Common-Pool Resource

ABSTRACT The introduction of property rights to manage common-pool resources is often met with opposition from some incumbent users, despite evidence of large aggregate increases in resource rent. We introduce an analytical model with firm heterogeneity to distinguish between traditional resource rent, which accrues to all owners, and inframarginal rent, which accrues to those with high skill. We show that, in the presence of skill heterogeneity, some current users (namely those with the highest skill) may prefer common-pool management, despite large aggregate increases in rents due to rationalization. Whether the transition to property rights is Pareto improving hinges critically on the initial allocation of rights, because inframarginal rents may be lower under property rights than limited entry. In our application to an important US fishery, property rights generate a ten-fold increase in market capitalization and a doubling in the present value of the resource, but without substantial free grandfather...

Resource Allocation for Cognitive Satellite Communications With Incumbent Terrestrial Networks

The lack of available unlicensed spectrum together with the increasing spectrum demand by multimedia applications has resulted in a spectrum scarcity problem, which affects satellite communications (SatCom) as well as terrestrial systems. The goal of this paper is to propose resource allocation (RA) techniques, i.e., carrier, power, and bandwidth allocation, for a cognitive spectrum utilization scenario where the satellite system aims at exploiting the spectrum allocated to terrestrial networks as the incumbent users without imposing harmful interference to them. In particular, we focus on the microwave frequency bands 17.7–19.7 GHz for the cognitive satellite downlink and 27.5–29.5 GHz for the cognitive satellite uplink, although the proposed techniques can be easily extended to other bands. In the first case, assuming that the satellite terminals are equipped with multiple low block noise converters (LNB), we propose a joint beamforming and carrier allocation scheme to enable cognitive space-to-Earth communications in the shared spectrum where fixed service (FS) microwave links have priority of operation. In the second case, however, the cognitive satellite uplink should not cause harmful interference to the incumbent FS system. For the latter, we propose a joint power and carrier allocation (JPCA) strategy followed by a bandwidth allocation scheme, which guarantees protection of the terrestrial FS system while maximizing the satellite total throughput. The proposed cognitive satellite exploitation techniques are validated with numerical simulations considering realistic system parameters. It is shown that the proposed cognitive exploitation framework represents a promising approach for enhancing the throughput of conventional satellite systems.

Towards trustworthy collaboration in spectrum sensing for ad hoc cognitive radio networks

Cognitive radio networks (CRN) make use of dynamic spectrum access to communicate opportunistically in frequency bands otherwise licensed to incumbent primary users such as TV broadcast. To prevent interference to primary users it is vital for secondary users in CRNs to conduct accurate spectrum sensing, which is especially challenging when the transmission range of primary users is shorter compared to the size of the CRN. This task becomes even more challenging in the presence of malicious secondary users that launch spectrum sensing data falsification (SSDF) attacks by providing false spectrum reports. Existing solutions to detect such malicious behaviors cannot be utilized in scenarios where the transmission range of primary users is limited within a small sub-region of the CRN. In this paper, we present a framework for trustworthy collaboration in spectrum sensing for ad hoc CRNs. This framework incorporates a semi-supervised spatio-spectral anomaly/outlier detection system and a reputation system, both designed to detect byzantine attacks in the form of SSDF from malicious nodes within the CRN. The framework guarantees protection of incumbent primary users' communication rights while at the same time making optimal use of the spectrum when it is not used by primary users. Simulation carried out under typical network conditions and attack scenarios shows that our proposed framework can achieve spectrum decision accuracy up to 99.3 % and detect malicious nodes up to 98 % of the time.

An evolution toward cognitive cellular systems: licensed shared access for network optimization

This article reviews the application of the recent European Licensed Shared Access (LSA) concept for spectrum sharing between a mobile network operator (MNO) and an incumbent user. LSA, as a new area of application of cognitive technology, provides the MNO an opportunity to access new frequency resources on a shared basis. The article presents critical design criteria of LSA from the MNO point of view in order to allow future cognitive cellular networks to efficiently exploit shared spectrum bands. We describe the role of LSA bands in the context of heterogeneous networking, and identify the Long Term Evolution (LTE) and LTE-Advanced enabling technologies that support the introduction of LSA. Such technologies include traffic steering, carrier aggregation, and self-organizing networking. Additionally, we introduce an LSA management unit controlled by the MNO, to be implemented on top of the existing LTE/LTEAdvanced architecture, and we discuss the functionalities required for the optimization and automation of LSA resource management. We also depict the interrelations of the tasks between the LSA management unit and the supporting LTE/LTE-Advanced technologies. Based on the findings in this article, the ongoing cellular system evolution is shown to form a solid base for the introduction of new shared spectrum bands for cognitive cellular systems.

Multi-user Cognitive Interference Channels: A Survey and New Capacity Results

This paper provides a survey of the state-of-the-art information theoretic analysis for overlay multi-user (more than two pairs) cognitive networks and reports new capacity results. In an overlay scenario, cognitive/secondary users share the same frequency band with licensed/primary users to efficiently exploit the spectrum. They do so without degrading the performance of the incumbent users, and may possibly even aid in transmitting their messages as cognitive users are assumed to possess the message(s) of primary user(s) and possibly other cognitive user(s). The survey begins with a short overview of the two-user overlay cognitive interference channel. The evolution from two-user to three-user overlay cognitive interference channels is described next, followed by generalizations to multi-user (arbitrary number of users) cognitive networks. The rest of the paper considers $K$ -user cognitive interference channels with different message knowledge structures at the transmitters. Novel capacity inner and outer bounds are proposed. Channel conditions under which the bounds meet, thus, characterizing the information theoretic capacity of the channel, for both linear deterministic and Gaussian channel models, are derived. The results show that for certain channel conditions distributed cognition, or having a cumulative message knowledge structure at the nodes, may not be worth the overhead as (approximately) the same capacity can be achieved by having only one global cognitive user whose role is to manage all the interference in the network. This paper concludes with future research directions.

CORHYS: Hybrid signaling for opportunistic distributed cognitive radio

Opportunistic cognitive radio (CR) allows unlicensed wireless nodes to dynamically locate and access spectrum holes, i.e., licensed channels that are not being used by their incumbent users. In this context, sensing the spectrum is a key issue and performing it on a data frame basis maximizes the protection of incumbent users. Additionally, when the architecture of a CR network is distributed (i.e., ad hoc), there are no central entities that perform operations such as collecting and fusing data, and taking spectrum decisions. Therefore, CR users (i.e., secondary users) must take their own decisions and cooperate with each other in order to exchange relevant information and coordinate access to the vacant channels. To achieve this goal, the utilization of a dedicated common control channel (CCC) is a common approach since it makes implementation and cooperation easier. However, a CCC can also saturate and become a bottleneck to performance, especially when handshake is performed on a data frame basis. In this paper, we define an approach that performs signaling over the CCC and over the allocated data channels simultaneously, i.e., out-of-band signaling and in-band signaling, respectively. This medium control access-level approach, which we designate as CORHYS (Cognitive Radio Hybrid Signaling), still takes advantage of the strengths of out-of-band signaling, effectively limits the CCC saturation problem, and, therefore, has potential to improve the communication performance of secondary users in distributed CR scenarios, particularly when they perform handshake and sensing on a data frame basis, and utilize a dedicated CCC. Simulation results are conclusive.

Heuristically Accelerated Reinforcement Learning for Dynamic Secondary Spectrum Sharing

This paper examines how flexible cellular system architectures and efficient spectrum management techniques can be used to play a key role in accommodating the exponentially increasing demand for mobile data capacity in the near future. The efficiency of the use of radio spectrum for wireless communications can be dramatically increased by dynamic secondary spectrum sharing; an intelligent approach that allows unlicensed devices access to those parts of the spectrum that are otherwise underutilized by the incumbent users. In this paper, we propose a heuristically accelerated reinforcement learning (HARL)-based framework, designed for dynamic secondary spectrum sharing in Long Term Evolution cellular systems. It utilizes a radio environment map as external information for guiding the learning process of cognitive cellular systems. System level simulations of a stadium temporary event scenario show that the schemes based on the proposed HARL framework achieve high controllability of spectrum sharing patterns in a fully autonomous way. This results in a significant decrease in the primary system quality of service degradation due to interference from the secondary cognitive systems, compared with a state-of-the-art reinforcement learning solution and a purely heuristic typical LTE solution. The spectrum sharing patterns that emerge by using the proposed schemes also result in remarkable reliability of the cognitive eNodeB on the aerial platform. Furthermore, the novel principle and the general structure of heuristic functions proposed in the context of HARL are applicable to a wide range of self-organization problems beyond the wireless communications domain.

The role of economics in transboundary restoration water management in the Colorado River Delta

Abstract In fully allocated rivers, providing restoration flows requires water transfers from incumbent users. Such transfers are often contested and are complicated within federal rivers and international rivers. In this paper, we investigate ecological restoration flows in the Colorado River Basin, a basin that spans seven U.S. states, two Mexican states, and contains significant estuarine and wetland ecosystems. Our investigation of a one-time pulse flow for the Delta illustrates the potential of fundamental economic concepts (opportunity cost, marginal analysis, and Pareto-improving compensation) in developing restoration options. Specifically, through the quantification of trade-offs from water transfers, provision of guidance on how to affect such water transfers at least-cost to society, and the identification of “win–win” opportunities. For instance, we find that whole-basin scale management not only enables transboundary financial and water transfers but also supports creative options for water resources management such as the utilization of transboundary storage. We discuss new opportunities within the U.S.–Mexico Treaty framework that support transboundary restoration and the tension between this readiness to cooperate and competition for low cost water transfers.

Harmful Interference and Its Role in Spectrum Policy

Radio spectrum has been subject to national and international regulation almost from its earliest days. “Harmful interference” is a key concept used by regulators in determining whether the impact of a proposed change in permitted radio use is acceptable vis-a-vis incumbent users. While the definition of harmful interference may have been adequate when it was first adopted decades ago, modern radio technology results in many situations where the definition is ambiguous. Clarifying the concept may improve regulatory certainty for developers of new radio technology while also improving the protection of incumbent users.

Resource management for QoS support in cognitive radio networks

Cognitive radio technology is a key enabler to reuse a finite, scarce, and expensive resource: the radio spectrum. Guaranteeing required levels of QoS to cognitive users and ensuring necessary protection to incumbent users are the two main challenges in opportunistic spectrum access. This article identifies the main requirements and challenges for QoS support in cognitive radio networks. A framework for a twofold cognitive manager is presented; one part managing spectrum availability on longer timescales and the other handling resource management on shorter timescales. This article gives particular focus to the functionalities of the latter cognitive manager related to resource management. Finally, we present a few key scenarios and describe how QoS can be managed with the proposed approach without disturbing the communications of incumbent users.

Decentralized Predictive MAC Protocol for Ad Hoc Cognitive Radio Networks

A new problem of spectrum scarcity has emerged due to the incredible technological advances in wireless communication. The spectrum scarcity issue is a bottleneck for the next generation of wireless communications. Therefore, efficient spectrum utilization has attracted considerable attention. This paper proposes a novel method of utilizing the white spaces in the licensed spectrum while ensuring the incumbent licensees' rights. The protocol predicts the incumbents' arrival using a historical prediction method and protects the incumbent users from the interference of opportunistic spectrum users. Distributed sensing is used to determine the network wide spectrum opportunity. The channel access delay in the proposed protocol is evaluated by simulation and mathematical analysis. The protocol has the advantages of a decentralized system, flexibility and low computing complexity. The simulations show that the protocol outperforms the existing opportunistic spectrum-sharing, media-access-control protocols in terms of the goodput and delay.

Robust spectrum sensing based on statistical tests

Spectrum sensing, in particular, detecting the presence of licensed or incumbent users in licensed spectrum, is one of the pivotal tasks in cognitive radio network. In this study, the authors tackle the spectrum sensing problem by using statistical test theory and derive novel spectrum sensing approaches. The authors apply the classical Kolmogorov–Smirnov (KS) test under the assumption that the noise probability distribution is known. However, as in practice, the exact noise distribution is unknown, a sensing method for Gaussian noise with unknown noise power is proposed in this article and referred to t-sensing. The proposed sensing scheme is asymptotically robust and can be applied to non-Gaussian noise distributions. A closed form equation determining the miss-detection probability for the t-sensing is derived. The authors compare with the performance of our sensing algorithms with the energy detector and Anderson–Darling (AD) sensing methods proposed in literature. Simulation results show that the proposed sensing methods outperform both ED- and AD-based sensing, especially for the case when the received signal-to-noise ratio is low.