Results 1 - 10 of 106

Mining Spectrum Usage Data: a Large-scale Spectrum Measurement Study

by Dawei Chen, Sixing Yin, Qian Zhang, Mingyan Liu, Qian Zhang , 2009
"... Dynamic spectrum access has been a subject of extensive study in recent years. The increasing volume of literature calls for a deeper understanding of the characteristics of current spectrum utilization. In this paper we present a detailed spectrum measurement study, with data collected in the 20MHz ..."
Abstract - Cited by 49 (2 self) - Add to MetaCart
Dynamic spectrum access has been a subject of extensive study in recent years. The increasing volume of literature calls for a deeper understanding of the characteristics of current spectrum utilization. In this paper we present a detailed spectrum measurement study, with data collected in the 20MHz to 3GHz spectrum band and at four locations concurrently in Guangdong province of China. We examine the first and second order statistics of the collected data, including channel occupancy/vacancy statistics, channel utilization within each individual wireless service, and the temporal, spectral, and spatial correlation of these measures. Main findings include that the channel vacancy durations follow an exponential-like distribution, but are not independently distributed over time, and that significant spectral and spatial correlations are found between channels of the same service. We then exploit such spectrum correlation to develop a 2-dimensional frequent pattern mining algorithm that can accurately predict channel availability based on past observations.
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Delay analysis for cognitive radio networks with random access: A fluid queue view

by Shanshan Wang, Junshan Zhang, Lang Tong - In Proc. IEEE INFOCOM , 2010
"... Abstract—We consider a cognitive radio network where multiple secondary users (SUs) contend for spectrum usage, using random access, over available primary user (PU) channels. Our focus is on SUs ’ queueing delay performance, for which a systematic understanding is lacking. We take a fluid queue app ..."
Abstract - Cited by 32 (8 self) - Add to MetaCart
Abstract—We consider a cognitive radio network where multiple secondary users (SUs) contend for spectrum usage, using random access, over available primary user (PU) channels. Our focus is on SUs ’ queueing delay performance, for which a systematic understanding is lacking. We take a fluid queue approximation approach to study the steady-state delay performance of SUs, for cases with a single PU channel and multiple PU channels. Using stochastic fluid models, we represent the queue dynamics as Poisson driven stochastic differential equations, and characterize the moments of the SUs ’ queue lengths accordingly. Since in practical systems, a secondary user would have no knowledge of other users ’ activities, its contention probability has to be set based on local information. With this observation, we develop adaptive algorithms to find the optimal contention probability that minimizes the mean queue lengths. Moreover, we study the impact of multiple channels and multiple interfaces, on SUs’ delay performance. As expected, the use of multiple channels and/or multiple interfaces leads to significant delay reduction. I.
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MAP: Multiauctioneer progressive auction for dynamic spectrum access

by Lin Gao, Student Member, Youyun Xu, Xinbing Wang - IEEE Transactions on Mobile Computing , 2011
"... Abstract—Cognitive radio (CR) is a promising paradigm to achieve efficient utilization of the limited spectrum resource by allowing the unlicensed users to access the licensed spectrum, and dynamic spectrum access (DSA) is one of the fundamental functions of CR networks. Market-driven spectrum aucti ..."
Abstract - Cited by 24 (4 self) - Add to MetaCart
Abstract—Cognitive radio (CR) is a promising paradigm to achieve efficient utilization of the limited spectrum resource by allowing the unlicensed users to access the licensed spectrum, and dynamic spectrum access (DSA) is one of the fundamental functions of CR networks. Market-driven spectrum auction has been recognized as an effective way to achieve DSA. In spectrum auction, the primary spectrum owners (POs) act as auctioneers who are willing to sell idle spectrum bands for additional revenue, and the secondary users (SUs) act as bidders who are willing to buy spectrum bands from POs for their services. However, conventional spectrum auction designs are restricted within the scenario of single auctioneer. In this paper, we study the spectrum auction with multiple auctioneers and multiple bidders, which is more realistic for practical CR networks. We propose MAP, a Multiauctioneer Progressive auction mechanism, in which each auctioneer systematically raises the trading price and each bidder subsequently chooses one auctioneer for bidding. The equilibrium is defined as the state that no auctioneer and bidder would like to change his decision. We show analytically that MAP converges to the equilibrium with maximum spectrum utilization of the whole system. We further analyze the incentive for POs and SUs joining the auction and accepting the auction result. Simulation results show that MAP well converges to the equilibrium, and the spectrum utilization is arbitrary closed to the global optimal solution according to the length of step. Index Terms—Cognitive radio, dynamic spectrum access, auction theory, spectrum auction, dual theory. Ç 1
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Channel sensing-order setting in cognitive radio networks: a two-user case

by Rongfei Fan, Hai Jiang - IEEE Trans. Veh. Technol , 2009
"... Abstract—This paper investigates the sensing-order problem in two-user multichannel cognitive medium access control. When adaptive modulation is not adopted, although brute-force search can be used to find the optimal sensing-order setting of the two users, it has huge computational complexity. Acco ..."
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Abstract—This paper investigates the sensing-order problem in two-user multichannel cognitive medium access control. When adaptive modulation is not adopted, although brute-force search can be used to find the optimal sensing-order setting of the two users, it has huge computational complexity. Accordingly, we propose two suboptimal algorithms, namely, the greedy search algorithm and the incremental algorithm, which have comparable performance with that of brute-force search and have much less computational complexity. It is shown that, with a high proba-bility, either suboptimal algorithm can reach an optimal point if a backoff mechanism is used for contention resolution. When adaptive modulation is adopted, it is observed that the traditional stopping rule does not lead to an optimal point in the two-user case. Furthermore, we demonstrate that the adoption of adaptive modulation affects the optimal sensing-order setting of the two users, compared with the case without adaptive modulation. These findings imply that the stopping rule and the sensing-order setting should be jointly designed from a systematic point of view. Index Terms—Cognitive radio, multiple access. I.
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On video multicast in cognitive radio networks

by Donglin Hu, Shiwen Mao, Jeffrey H. Reed - in Proc. IEEE INFOCOM’09, Rio de Janeiro , 2009
"... Abstract — We investigate the challenging problem of enabling multicast video service in emerging cognitive radio (CR) net-works. We propose a cross-layer optimization approach to multicast video in CR networks. Specifically, we model CR video multicast as an optimization problem, while considering ..."
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Abstract — We investigate the challenging problem of enabling multicast video service in emerging cognitive radio (CR) net-works. We propose a cross-layer optimization approach to multicast video in CR networks. Specifically, we model CR video multicast as an optimization problem, while considering important design factors including scalable video coding, video rate control, spectrum sensing, dynamic spectrum access, modu-lation, scheduling, retransmission, and primary user protection. The objective is to optimize the overall received video quality as well as achieving proportional fairness among multicast users, while keeping the interference to primary users below a prescribed threshold. Although the problem can be solved using advanced optimization techniques, we propose a sequential fixing algorithm and a greedy algorithm with low complexity and proven optimality gap. Our simulations using MPEG-4 fine grained scalability (FGS) demonstrate the efficacy and superior performance of the proposed approach as compared with an alternative equal allocation scheme. I.

Prediction-Based Topology Control and Routing in Cognitive Radio Mobile Ad Hoc Networks

by Quansheng Guan, Student Member, F. Richard Yu, Senior Member, Shengming Jiang, Senior Member, Gang Wei, Senior Member - IEEE Transactions on Vehicular Technology , 2010
"... Abstract—Recent research activities on cognitive radio (CR) have mainly focussed on opportunistic spectrum access and spec-trum utilization. However, CR technology will have a significant impact on upper layer performance in wireless networks, partic-ularly in mobile ad hoc networks (MANETs). In thi ..."
Abstract - Cited by 13 (0 self) - Add to MetaCart
Abstract—Recent research activities on cognitive radio (CR) have mainly focussed on opportunistic spectrum access and spec-trum utilization. However, CR technology will have a significant impact on upper layer performance in wireless networks, partic-ularly in mobile ad hoc networks (MANETs). In this paper, we study topology control and routing issues in CR-MANETs and propose a distributed prediction-based cognitive topology control (PCTC) scheme to provision cognition capability to routing in CR-MANETs. PCTC is a middleware-like cross-layer module re-siding between CR module and routing. It uses cognitive link avail-ability prediction, which is aware of the interference to primary users and user mobility, to predict the available duration of links. Based on the link prediction, PCTC captures the dynamic changes of the topology and constructs an efficient and reliable topology, which is aimed at mitigating rerouting frequency and improving end-to-end network performance such as throughput and delay. Simulation results are presented to show the effectiveness of the proposed scheme. Index Terms—Cognitive radio (CR), link-availability predic-tion, mobile ad hoc network (MANET), routing, topology control. I.
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QoS Provisioning for Heterogeneous Services in Cooperative Cognitive Radio Networks

by Ammar Alshamrani, Xuemin (sheman Shen, Liang-liang Xie, Senior Member
"... Abstract—In this paper, we propose a spectrum allocation framework that jointly considers the Quality-of-Service (QoS) provisioning for heterogeneous secondary Real-Time (RT) and Non-Real Time (NRT) users, the spectrum sensing, spectrum access decision, channel allocation, and call admission control ..."
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Abstract—In this paper, we propose a spectrum allocation framework that jointly considers the Quality-of-Service (QoS) provisioning for heterogeneous secondary Real-Time (RT) and Non-Real Time (NRT) users, the spectrum sensing, spectrum access decision, channel allocation, and call admission control in distributed cooperative Cognitive Radio Networks (CRNs). Giving priority to the RT users with QoS requirements in terms of the dropping and blocking probabilities, a number of the identified available channels are allocated to the optimum number of the RT users that can be admitted into the network, while the remaining identified available channels are allocated adaptively to the optimum number of the NRT users considering the spectrum sensing and utilization indispensability. Extensive analytical and simulation results are provided to demonstrate the effectiveness of the proposed QoS-based spectrum resource allocation framework.
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On medium grain scalable video streaming over cognitive radio femtocell networks

by Donglin Hu, Shiwen Mao, Senior Member - IEEE J. Sel. Areas Commun , 2012
"... Abstract—Femtocells are shown highly effective on improving network coverage and capacity by bringing base stations closer to mobile users. In this paper, we investigate the problem of streaming scalable videos in femtocell cognitive radio (CR) networks. This is a challenging problem due to the stri ..."
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Abstract—Femtocells are shown highly effective on improving network coverage and capacity by bringing base stations closer to mobile users. In this paper, we investigate the problem of streaming scalable videos in femtocell cognitive radio (CR) networks. This is a challenging problem due to the stringent QoS requirements of real-time videos and the new dimensions of network dynamics and uncertainties in CR networks. We develop a framework that captures the key design issues and trade-offs with a stochastic programming problem formulation. In the case of a single FBS, we develop an optimum-achieving distributed algorithm, which is shown also optimal for the case of multiple non-interfering FBS’s. In the case of interfering FBS’s, we develop a greedy algorithm that can compute near-optimal solutions, and prove a closed-form lower bound on its performance. The proposed algorithms are evaluated with simulations, and are shown to outperform three alternative schemes with considerable margins. Index Terms—Cognitive radio, cross-layer optimization, fem-tocell, Medium Grain Scalable video, stochastic programming.
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Delay Performance Analysis for Supporting Real-Time Traffic ina Cognitive Radio Sensor Network

by Zhongliang Liang, Shan Feng, Dongmei Zhao, Xuemin (sherman Shen
"... Abstract—Traditional wireless sensor networks (WSNs) working in the license-free spectrum suffer from uncontrolled interference as the license-free spectrum becomes increasingly crowded. Designing a WSN based on cognitive radio can be promising in the near future in order to provide data transmissio ..."
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Abstract—Traditional wireless sensor networks (WSNs) working in the license-free spectrum suffer from uncontrolled interference as the license-free spectrum becomes increasingly crowded. Designing a WSN based on cognitive radio can be promising in the near future in order to provide data transmissions with quality of service requirements. In this paper we introduce a cognitive radio sensor network (CRSN) and analyze its performance for supporting real-time traffic. The network opportunistically accesses vacant channels in the licensed spectrum. When the current channel becomes unavailable, the devices can switch to another available channel. Two types of channel switchings are considered, in periodic switching (PS) the devices can switch to a new channel only at the beginning of each channel switching (CS) interval, while in triggered switching (TS) the devices can switch to a new channel as soon as the current channel is lost. We consider two types of real-time traffic, i) a burst of packets are generated periodically and the number of packets in each burst is random, and ii) packet arrivals follow a Poisson process. We derive the average packet transmission delay for each type of the traffic and channel switching mechanisms. Our results indicate that real-time traffic can be effectively supported in the CRSN with small average packet transmission delay. For the network using PS, packets with the Poisson arrivals experience longer average delay than the bursty arrivals; while for the network using TS, packets with the bursty arrivals experience longer average delay. Index Terms—Wireless sensor networks, cognitive radio networks, real-time traffic, performance analysis. I.
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Throughput and Delay Bounds for Cognitive Transmissions

by F. Borgonovo, M. Cesana, L. Fratta - In Proc. Med-Hoc-Net’08 , 2008
"... Abstract Cognitive networks are based on agile and opportunistic use of spectrum resources. This work focuses on those network scenarios where primary or licensed users coexist with secondary or unlicensed ones. Secondary users opportunistically access the shared resources whenever vacant, with the ..."
Abstract - Cited by 10 (0 self) - Add to MetaCart
Abstract Cognitive networks are based on agile and opportunistic use of spectrum resources. This work focuses on those network scenarios where primary or licensed users coexist with secondary or unlicensed ones. Secondary users opportunistically access the shared resources whenever vacant, with the strict constraint of being invisible to primary users. We derive here analytical bounds on throughput and transmission delay of secondary users under different assumptions on secondary and primary users traffic statistics, and we comment on the use of the proposed models to dimension secondary transmissions. 1
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