Spectrum Access Model Research Articles

Performance analysis of CR-honeynet to prevent jamming attack through stochastic modeling

Cognitive Radio Network (CRN) has to stall its packet transmission periodically to sense the spectrum for Primary User’s (PU’s) transmission. The limited and dynamically available spectrum and fixed periodic schedule of transmission interruption makes it harder to model the performance of a CRNs. Again, an open and dynamic spectrum access model brings forth a serious challenge of sustenance among the CRN and makes them more susceptible to jamming-based denial of service (DoS) attacks. Inspired by honeypot in the network security, we propose a honeynet based defense mechanism called CR-honeynet. CR-honeynet aims to avoid attacks on legitimate communications by dedicating a Secondary User (SU) as a honeynode, to deter the attacker from attacking legitimate SUs and attack the honeynode instead. Dedicating an SU as honeynode, on account of its permanent idleness, is wasteful of an entire node as a resource. We seek to resolve the dilemma by dynamically selecting the honeynode for each transmission period. The contribution of the current paper is two-fold. Initially, we develop the first comprehensive queuing model for CRNs, which pose unique modeling challenges, due to their fixed periodic sensing and transmission cycles. In the second step, we introduce a series of strategies for honeynode selection to combat these attacks while keeping the CRN’s performance optimal for different traffic scenarios. We build a simulation of a CRN under jamming attack and analyze its performance with different honeynode selection strategies. We find that the predictions, of our mathematical model, track closely with the results of our simulation experiments.

Truthful Spectrum Auctions With Approximate Social-Welfare or Revenue

In cellular networks, a recent trend in research is to make spectrum access dynamic in the spatial and temporal dimensions for the sake of efficient utilization of spectrum. In one such model, the spectrum is divided into channels and periodically allocated to competing base stations using an auction-based market mechanism. An “efficient” auction mechanism is essential to the success of such a dynamic spectrum access model. A key objective in designing an auction mechanism is “truthfulness.” Combining this objective with an optimization of some social choice function (such as the social-welfare or the generated revenue) is highly desirable. In this paper, we design polynomial-time spectrum auction mechanisms that are truthful and yield an allocation with $O(1)$ -approximate social-welfare or revenue. Our mechanisms generalize to general interference models. To the best of our knowledge, ours is the first work to design polynomial-time truthful spectrum auction mechanisms with a constant-factor approximation of either the expected revenue or the social-welfare. We demonstrate the performance of our designed mechanism through simulations.

Cognitive cross-layer multipath probabilistic routing for cognitive networks

Mobile Ad-hoc NETworks (MANETs) is a set of mobile nodes that can move around arbitrarily, and communicate with others in a multi-hop fashion without any assistance of base stations. With recent advances in Cognitive Radio (CR) technology, it is possible to apply the Dynamic Spectrum Access model in MANETs. This introduces the concept of Cognitive Radio Ad Hoc Networks (CRAHNs). Applying CR techniques provides better throughput, even in congested spectrum along with better propagation characteristics. CRAHN is a kind of intelligent network that is aware of its surrounding environment, and adapts to the transmission or reception parameters to achieve efficient communication without interfering with primary users. Routing in CR environment is a challenging task as the availability of channel is constrained by the presence of primary user. The problem of routing in CRAHNs targets the creation and maintenance of wireless multi-hop paths among cognitive nodes by deciding both the spectrum to be used and the relay nodes of the path. This paper proposes a cognitive cross-layer multipath probabilistic routing for cognitive radio based networks. The proposed solution uses spectrum holes identified by MAC layer, decides the channel to be used and transmit power level for each hop in the path. The proposed solution is implemented in NS2, and performance of the proposed solution is compared with the existing solution from the literature. The paper also shows that the proposed solution outperforms existing solution in terms of packet delivery ratio, average end-to-end delay and energy consumed per data packet.

3~4 GHz 대 주파수 공동사용을 위한 스펙트럼 액세스 모델 제안

Abstract Many researches on the usage of shared spectrum have continuously been carried out to solve the recent frequency shortage problem and to use efficiently the spectrum without interference. Also, exponential mobile data growth and the solutions needed to address this challenge are parallel key objectives addressed in many countries. Spectrum policy innovation to meet this challenge is the ASA/LSA (Authorized Shared Access/Licensed Shared Access), which is the best access model to employ the small cell technology to meet this mobile traffic growth. Because 3.5 GHz bands is considered as the ASA/LSA frequency, in this paper, we propose the SAM(Spectrum Access Model) in 34 GHz bands to estimate the available ASA/LSA bands and to open more free spectrum. These results are utilized as the data to develop the SAM for the small cell and the open frequency in future.Key words: Spectrum Sharing, ASA/LSA, Small Cell pqr Revised July 30, 2014 ; Accepted August 12, 2014. (ID No. 20140625-02S)Corresponding Author: Young-Heung Kang (e-mail: yhkang@kunsan.ac.kr)

A Survey on Dynamic Spectrum Access via Cognitive Radio: Taxonomy, Requirements, and Benefits

Conventionally, interference protection among radio spectrum users is guaranteed through a policy of spectrum licensing that provides exclusive access to licensed users. However, as it is becoming extremely difficult to satisfy the growing demand for radio spectrum with this conventional policy, a flexible policy that can improve radio spectrum access and utilization without causing interference amongst users has recently gained increasing interest. In this context, this paper presents a comprehensive survey on flexible radio spectrum management with full focus on a cognitive radio technology application for dynamic spectrum access. The study approach involves analytical evaluation of the performance of the current fixed radio spectrum allocation policy examining both technical and economic perspectives. The result of which shows that the current fixed radio spectrum management policy is too rigid, inefficient and out-dated and needed to be replaced with a flexible radio spectrum management policy. Based on this analytical result, an in-depth survey on innovative technology and standards for a dynamic spectrum management model that can enhance an increase in spectral utilization and coexistence of multiple radios with adequate interference free communication was carried out. The paper also discusses the interrelationship between technologies, business and policies for cognitive radio standardization for seamless wireless communication. In addition, the paper presents both the technical and economic benefits of the dynamic radio spectrum management model over the current fixed radio spectrum allocation policy. The paper was finally concluded recommending the commercial adoption of dynamic spectrum access worldwide keeping in mind all the benefits of the dynamic spectrum access model and standards in place to ensure interference free communication in a cognitive radio environment.

Spectrum Trading for Non-Identical Channel Allocation in Cognitive Radio Networks

In this paper, we investigate spectrum trading via auction approach for exclusive usage spectrum access model in cognitive radio networks. We consider a realistic valuation function which depends on channel capacity, delay sensitive and delay-insensitive data traffics of secondary users (SUs), and propose an efficient concurrent Vickrey-Clarke-Grove (VCG) mechanism for non-identical channel allocation among r-minded bidders in two different cases. In the first case, the SUs are r-minded but they can submit bid only for single channels. In the second case, the SUs are r-minded and they can submit bid for bundles of channels. We show that the first case is solvable in polynomial time but in the other one, the problem of determining auction outcomes is NP-hard. We propose two sub-optimal methods for solving this problem, namely greedy algorithm and randomized rounding linear programming (LP) relaxation algorithm. Due to the sub-optimal nature of solutions in the second case, VCG mechanism is not truthful anymore and the SUs can lie to maximize their utilities. To address this, we propose an auction mechanism with limited truthfulness property based on an iterative greedy algorithm.

Priority-based classification of spectrum access models [Accepted From Open Call

The reforms in spectrum management aim toward more efficient, flexible, and shared use of spectrum, while fostering innovation and competition in mobile communications. The goal is to have affordable wireless broadband and make Internet access a human right. To achieve this goal, the regulators need to identify, evaluate, and decide between the different spectrum access models. This article presents a taxonomy of the models, which is based on priorities between the different users of spectrum. For example, the low priority systems may be allowed to use the spectrum only if the high priority systems are not occupying the frequency. The hierarchy of the systems can be implemented using different technologies such as centralized databases or distributed sensing devices. The taxonomy clarifies the regulatory alternatives and emphasizes the differences in ownership and usage rights. The new models can be incorporated in the auction design in order to estimate their value to the companies, and this reflects the recent trend of supporting spectrum management with market- based methods.

Scheme for opportunistic spectrum access in cognitive radio

In this study, an opportunistic spectrum access model with learning strategy is presented for cognitive radio system. Consider a hidden Markov model in learning process, where the ternary hypothesis testing scheme is proposed to perform sensing with the goodness of fit testing. By using a gradient method, the secondary user can estimate the channel patterns and keep up with the variations of the primary user activities. An opportunistic access channel capacity is introduced to evaluate the quality of service of the objective licensed channel. Also, a partially observable Markov decision process framework is presented to exploit spectrum holes. Further analysis shows that, unlike the binary hypothesis testing where the idle state is always protected, the idea of the proposed ternary hypothesis testing puts both the idle and busy state in the same position, which reflects the real state of the licensed channel more precisely. Simulation results indicate that the proposed ternary hypothesis testing scheme outperforms the conventional binary hypothesis testing for both the goodness of fit testing and the energy detection.

Ternary Hypothesis Testing Scheme for Rapidly Opportunistic Spectrum Access

This letter presents a partially observable Markov decision process framework for the opportunistic spectrum access model, where a ternary hypothesis testing scheme is proposed to perform sensing with the goodness of fit testing. Except for idle and busy states, the proposed ternary hypothesis testing also considers the transition state, which reflects the real state of a licensed channel more precisely. Simulation results indicate that the proposed ternary hypothesis testing scheme achieves better performances in channel utilization and collision rate compared with those of the conventional binary hypothesis testing scheme, especially for the rapid variations of the primary user activities.

Distributed access control policies for spectrum sharing

ABSTRACTCognitive radio is a novel wireless communication technology that allows for adaptive configuration of the reception parameters of a terminal, based on the information collected from the environment. Cognitive radio technology can be used in innovative spectrum management approaches such as spectrum sharing, where radio frequency spectral bands can be shared among various users through a dynamic exclusive‐use spectrum access model. Spectrum sharing can be applied to various scenarios in the commercial, public safety and military domain. In some scenarios, spectrum sharing demands a mechanism for expressing and enforcing access control policies for the allocation of resources including spectral bands. The access control polices should state what are the available resources (e.g., transmission/reception bandwidths), what are the users that are allowed to access them and under what conditions. However, because of the intrinsically highly dynamic nature of specific scenarios (e.g., public safety, military), where parties with various levels of authority may suddenly appear, it may be difficult to establish in advance what are the most suitable access control policies. Trust negotiation is a well‐known approach for expressing and enforcing distributed access control policies that depend on two or more parties. In this work, we present a trust negotiation‐based framework that allows for the definition of highly expressive and flexible distributed access control policies for the allocation of spectrum resources. Copyright © 2012 John Wiley & Sons, Ltd.

Performance Analysis of Suboptimal Spectrum Sensing Algorithm in Cognitive Networks

Recently, both optimal and suboptimal spectrum sensing approaches have attracted extensive attention in wireless communications field. Thanks to opportunistic spectrum access schemes, different cognitive users can cooperatively search for and exploit instantaneous spectrum availability. In this paper, we address the analysis of spectrum sensing in opportunistic spectrum access models and then determine throughput of the cognitive radio system. Our goal in all designs is reach optimal access policy for each channel with the high cooperative sensing performances.

The Research of WSN Architecture for Smart Grid Utility

WSN (Wireless Sensor Networks) has been considered as one of the very promising technologies for the implementation of smart grid (SG). On the other hand, with recent advances in Cognitive Radio (CR) technology, it is possible to apply the Dynamic Spectrum Access (DSA) model in WSN to get access to less congested spectrum, possibly with better propagation characteristics. In this paper we investigate the application of WSN in smart grid and the structure of traditional WSN etc. For smart grid utility, a novel environment-adaptive and cross-layer architecture of CR-based WSN is proposed. Furthermore, the design methods, general characteristics and functions of every layer or every module are described and discussed.

Cooperative Spectrum Sensing using Kalman Filter based Adaptive Fuzzy System for Cognitive Radio Networks

Spectrum sensing is an important functionality for cognitive to look for spectrum holes before taking transmission in dynamic spectrum access model. Unlike previous works that assume perfect knowledge of the SNR of the signal received from the primary user, in this paper we consider a realistic case where the SNR of the primary users signal is unknown to both fusion center and cognitive radio terminals. A Kalman filter based adaptive Takagi and Sugenos fuzzy system is designed to make the global spectrum sensing decision based on the observed energies from cognitive users. With the capacity of adapting system parameters, the fusion center can make a global sensing decision reliably without any requirement of channel state information, prior knowledge and prior probabilities of the primary users signal. Numerical results prove that the sensing performance of the proposed scheme outperforms the performance of the equal gain combination based scheme, and matches the performance of the optimal soft combination scheme.

T-preemptive priority queue and its application to the analysis of an opportunistic spectrum access in cognitive radio networks

We propose a new priority discipline called the T-preemptive priority discipline. Under this discipline, during the service of a customer, at every T time units the server periodically reviews the queue states of each class with different queue-review processing times. If the server finds any customers with higher priorities than the customer being serviced during the queue-review process, then the service of the customer being serviced is preempted and the service for customers with higher priorities is started immediately. We derive the waiting-time distributions of each class in the M/G/1 priority queue with multiple classes of customers under the proposed T-preemptive priority discipline. We also present lower and upper bounds on the offered loads and the mean waiting time of each class, which hold regardless of the arrival processes and service-time distributions of lower-class customers. To demonstrate the utility of the T-preemptive priority queueing model, we take as an example an opportunistic spectrum access in cognitive radio networks, where one primary (licensed) user and multiple (unlicensed) users with distinct priorities can share a communication channel. We analyze the queueing delays of the primary and secondary users in the proposed opportunistic spectrum access model, and present numerical results of the queueing analysis.

An Application of Reinforcement Learning for Efficient Spectrum Usage in Next-Generation Mobile Cellular Networks

This paper proposes reinforcement learning as a foundational stone of a framework for efficient spectrum usage in the context of next-generation mobile cellular networks. The objective of the framework is to efficiently use the spectrum in a cellular orthogonal frequency-division multiple access network while unnecessary spectrum is released for secondary spectrum usage within a private commons spectrum access model. Numerical results show that the proposed framework obtains the best performance compared with other approaches for spectrum assignment. Moreover, the framework is relatively simple to implement in terms of computational requirements and signaling overhead.

Spectrum Sharing in an ISM Band: Outage Performance of a Hybrid DS/FH Spread Spectrum System with Beamforming

This paper investigates spectrum sharing issues in the unlicensed industrial, scientific, and medical (ISM) bands. It presents a radio frequency measurement setup and measurement results in 2.4 GHz. It then develops an analytical model to characterize the coexistence interference in the ISM bands, based on radio frequency measurement results in the 2.4 GHz. Outage performance using the interference model is examined for a hybrid direct-sequence frequency-hopping spread spectrum system. The utilization of beamforming techniques in the system is also investigated, and a simplified beamforming model is proposed to analyze the system performance using beamforming. Numerical results show that beamforming significantly improves the system outage performance. The work presented in this paper provides a quantitative evaluation of signal outages in a spectrum sharing environment. It can be used as a tool in the development process for future dynamic spectrum access models as well as engineering designs for applications in unlicensed bands.

Signal Classification in Fading Channels Using Cyclic Spectral Analysis

Cognitive Radio (CR), a hierarchical Dynamic Spectrum Access (DSA) model, has been considered as a strong candidate for future communication systems improving spectrum efficiency utilizing unused spectrum of opportunity. However, to ensure the effectiveness of dynamic spectrum access, accurate signal classification in fading channels at low signal to noise ratio is essential. In this paper, a hierarchical cyclostationary-based classifier is proposed to reliably identify the signal type of a wide range of unknown signals. The proposed system assumes no a priori knowledge of critical signal statistics such as carrier frequency, carrier phase, or symbol rate. The system is designed with a multistage approach to minimize the number of samples required to make a classification decision while simultaneously ensuring the greatest reliability in the current and previous stages. The system performance is demonstrated in a variety of multipath fading channels, where several multiantenna-based combining schemes are implemented to exploit spatial diversity.

Dynamic spectrum access models: toward an engineering perspective in the spectrum debate

Until recently, the proponents of spectrum commons and the proponents of spectrum property rights had settled, like the armies of the Marne, into their entrenched positions, emerging only to launch periodic and unproductive attacks across a semantic and philosophical no man's land. Recently, however, there have been calls to move beyond these entrenched positions, by developing pragmatic models and solutions that capture some of the benefits of each philosophical position. In this article we cautiously enter that no man's land with two illustrative dynamic spectrum access models. While both of our models retain a bias toward usage of spectrum resources based on a spectrum property rights approach, they also promote dynamic access and short-term dedication of spectrum resources. We call these models dynamic property rights spectrum access (D-Pass) and dynamic commons property rights spectrum access (D-CPass). In this work we focus primarily on engineering issues, proposing the use of a spectrum policy server as a clearinghouse and specifying the spectrum access mechanisms relevant to each model. To demonstrate the useful studies enabled through these models, we present illustrative results via the bandwidth utilization achieved under each model. Our results indicate that both the spectrum access mechanism and market forces will play important roles in determining the resulting bandwidth utilization.

Reliable Multimedia Transmission Over Cognitive Radio Networks Using Fountain Codes

With the explosive growth of wireless multimedia applications over the wireless Internet in recent years, the demand for radio spectral resources has increased significantly. In order to meet the quality of service, delay, and large bandwidth requirements, various techniques such as source and channel coding, distributed streaming, multicast etc. have been considered. In this paper, we propose a technique for distributed multimedia transmission over the secondary user network, which makes use of opportunistic spectrum access with the help of cognitive radios. We use digital fountain codes to distribute the multimedia content over unused spectrum and also to compensate for the loss incurred due to primary user interference. Primary user traffic is modelled as a Poisson process. We develop the techniques to select appropriate channels and study the trade-offs between link reliability, spectral efficiency and coding overhead. Simulation results are presented for the secondary spectrum access model.