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Channel quality prediction based on bayesian inference in cognitive radio networks
- in IEEE INFOCOM
, 2013
"... Abstract—The problem of channel quality prediction in cog-nitive radio networks is investigated in this paper. First, the spectrum sensing process is modeled as a Non-Stationary Hidden Markov Model (NSHMM), which captures the fact that the chan-nel state transition probability is a function of the t ..."
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Abstract—The problem of channel quality prediction in cog-nitive radio networks is investigated in this paper. First, the spectrum sensing process is modeled as a Non-Stationary Hidden Markov Model (NSHMM), which captures the fact that the chan-nel state transition probability is a function of the time interval the primary user has stayed in the current state. Then the model parameters, which carry the information about the expected duration of the channel states and the spectrum sensing accuracy (detection accuracy and false alarm probability) of the SU, are estimated via Bayesian inference with Gibbs sampling. Finally, the estimated NSHMM parameters are employed to design a channel quality metric according to the predicted channel idle duration and spectrum sensing accuracy. Extensive simulation study has been performed to investigate the effectiveness of our design. The results indicate that channel ranking based on the proposed channel quality prediction mechanism captures the idle state duration of the channel and the spectrum sensing accuracy of the SUs, and provides more high quality transmission opportunities and higher successful transmission rates at shorter spectrum waiting times for dynamic spectrum access. Index Terms—Channel quality prediction; cognitive radio networks; non-stationary HMM; Bayesian inference. I.
Optimal Primary-User Mobility Aware Spectrum Sensing Design for Cognitive Radio Networks
"... Abstract—A key issue of the spectrum sensing functionality in Cognitive Radio (CR) networks is the ability of tuning the sensing time parameters, i.e., the sensing time and the transmission time, according to the Primary User (PU) network dynamics. In fact, these parameters influence both the spectr ..."
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Abstract—A key issue of the spectrum sensing functionality in Cognitive Radio (CR) networks is the ability of tuning the sensing time parameters, i.e., the sensing time and the transmission time, according to the Primary User (PU) network dynamics. In fact, these parameters influence both the spectrum sensing efficiency and the PU interference avoidance. This issue becomes even more challenging in presence of PU mobility. In this paper, an optimal spectrum sensing design for mobile PU scenarios is proposed with the aim to achieve the following important features: i) to determine the optimal mobility-aware transmission time, i.e., the transmission time value that jointly maximizes the spectrum sensing efficiency and satisfies the PU interference constraint; ii) to determine the optimal mobility-aware sensing time threshold, i.e., the maximum sensing time value assuring efficient spectrum sensing. First, closed-form expressions of both the optimal transmission time and the optimal sensing time threshold are analytically derived for a general PU mobility model. Then, the derived expressions are specialized for two widely adopted mobility models, i.e., the Random Walk mobility Model with reflection and the Random Way-Point mobility Model. Practical rules for the sensing parameter tuning are provided with reference to the considered mobility models. The analytical results are finally validated through simulations. Index Terms—Mobility, spectrum sensing, cognitive radio. I.
Testbed for Cognitive Radio Networks Based on USRP2/N200 Modules
"... Abstract—This paper deals with description of software defined radio test-bed based on USRP2/N200 modules available from ETTUS research. The aim of this test-bed is to develop and test the algorithms for cognitive radio mobile networks. The primary focus is on the spectrum sensing in moving secondar ..."
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Abstract—This paper deals with description of software defined radio test-bed based on USRP2/N200 modules available from ETTUS research. The aim of this test-bed is to develop and test the algorithms for cognitive radio mobile networks. The primary focus is on the spectrum sensing in moving secondary users scenario, adaptation of the radio resource parameters and evaluation of sensitivity to security threats in the mobile cognitive radio networks. Besides the overall archi-tecture description, the paper presents used way to emulate the signals of various communication and broadcasting systems-designed incumbent system simulator and describes the basic implemented blocks- simple OFDM modem, spectrum sensing based on the cyclic prefix correlation and modified method for OFDM subcarrier allocation adaptation. Keywords-cognitive networks; sensing; resource allocation, attacks. I.
Delay-Constrained Caching in Cognitive Radio Networks
"... Abstract—In cognitive radio networks, unlicensed users can use under-utilized licensed spectrum to achieve substantial per-formance improvement. To avoid interference with licensed users, unlicensed users must vacate the spectrum when it is accessed by licensed (primary) users. Since it takes some t ..."
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Abstract—In cognitive radio networks, unlicensed users can use under-utilized licensed spectrum to achieve substantial per-formance improvement. To avoid interference with licensed users, unlicensed users must vacate the spectrum when it is accessed by licensed (primary) users. Since it takes some time for unlicensed users to switch to other available channels, the ongoing data transmissions may have to be interrupted and the transmission delay can be significantly increased. This makes it hard for cognitive radio networks to meet the delay constraints of many applications. To the best of our knowledge, we are the first to use caching techniques to address this problem. We formulate the cache placement problem in cognitive radio networks as an optimization problem, where the goal is to minimize the total cost, subject to some delay constraint, i.e., the data access delay can be statistically bounded. To solve this problem, we propose three approaches: cost-based, delay-based, and hybrid. Simulation results show that our approaches outperform existing caching solutions in terms of total cost and delay constraint, and the hybrid approach performs the best among the approaches satisfying the delay constraint. I.
Distributed and asynchronous data collection in cognitive radio networks with fairness consideration
- Proceedings of the IEEE Transactions on Parallel and Distributed Systems (TPDS
, 2013
"... Abstract-As a promising communication paradigm, Cognitive Radio Networks (CRNs) have paved a road for Secondary Users (SUs) to opportunistically exploit unused licensed spectrum without causing unacceptable interference to Primary Users (PUs). In this paper, we study the distributed data collection ..."
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Abstract-As a promising communication paradigm, Cognitive Radio Networks (CRNs) have paved a road for Secondary Users (SUs) to opportunistically exploit unused licensed spectrum without causing unacceptable interference to Primary Users (PUs). In this paper, we study the distributed data collection problem for asynchronous CRNs, which has not been addressed before. We study the Proper Carrier-sensing Range (PCR) for SUs. By working with this PCR, an SU can successfully conduct data transmission without disturbing the activities of PUs and other SUs. Subsequently, based on the PCR, we propose an Asynchronous Distributed Data Collection (ADDC) algorithm with fairness consideration for CRNs. ADDC collects a snapshot of data to the base station in a distributed manner without the time synchronization requirement. The algorithm is scalable and more practical compared with centralized and synchronized algorithms. Through comprehensive theoretical analysis, we show that ADDC is order-optimal in terms of delay and capacity, as long as an SU has a positive probability to access the spectrum. Furthermore, we extend ADDC to deal with the continuous data collection issue, and analyze the delay and capacity performances of ADDC for continuous data collection, which are also proven to be order-optimal. Finally, extensive simulation results indicate that ADDC can effectively accomplish a data collection task and significantly reduce data collection delay.
Mobile Access of Wide-Spectrum Networks: Design, Deployment and Experimental Evaluation
"... Abstract—Wireless networks increasingly utilize diverse spectral bands that exhibit vast differences in both transmission range and usage. In this work, we present MAWS (Mobile Access of Wide-Spectrum Networks), the first scheme designed for mobile clients to evaluate and select both APs and spectra ..."
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Abstract—Wireless networks increasingly utilize diverse spectral bands that exhibit vast differences in both transmission range and usage. In this work, we present MAWS (Mobile Access of Wide-Spectrum Networks), the first scheme designed for mobile clients to evaluate and select both APs and spectral bands in wide-spectrum networks. Because of the potentially vast number of spectrum and AP options, scanning may be prohibitive. Consequently, our key technique is for clients to infer channel quality and spectral usage for their current location and bands using limited measurements collected in other bands and at other locations. We experimentally evaluate MAWS via a widespectrum network that we deploy, a testbed providing access to four bands at 700 MHz, 900 MHz, 2.4 GHz and 5 GHz. To the best of our knowledge, the spectrum of these bands is the widest to be spanned to date by a single operational access network. A key finding of our evaluation is that under a diverse set of operating conditions, mobile clients can accurately predict their performance without a direct measurement at their current location and spectral bands. I.
This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. 1 A Distributed TDMA Scheduling Algorithm for Target Tracking in Ultrasonic Sensor Networks
"... Abstract—Ultrasonic sensors are able to provide highly accurate measurements, however, they have to be carefully scheduled otherwise the inter-sensor interference (ISI) would greatly deteriorate the performance. It is also preferred that the scheduling scheme can be performed in a distributed and en ..."
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Abstract—Ultrasonic sensors are able to provide highly accurate measurements, however, they have to be carefully scheduled otherwise the inter-sensor interference (ISI) would greatly deteriorate the performance. It is also preferred that the scheduling scheme can be performed in a distributed and energy-efficient way so that it can be conveniently implemented for largescale network. In this paper, for target tracking with multiple ultrasonic sensors, we convert the ISI avoidance problem to the problem of multiple access in a shared channel, and adopt the TDMA strategy which has the properties of collision-free and energy efficient. Then by graph theory, the scheduling problem is transformed into a coloring problem which aims at minimizing the number of used colors. Since the original problem has been proved to be NP-hard, we propose a distributed saturation degree based algorithm (DSDA) which can be implemented locally by each node with information collected from its neighbors. Furthermore, we verify that an interference-free schedule is guaranteed to be obtained by DSDA. We derive analytical results for the complexity of this algorithm. Specifically, for different sensor network topologies, we prove that the expected converging time and the expected message transmissions per node are both upper bounded by O(δ), where δ is the maximum neighborhood size in the network. Extensive simulations demonstrate the effectiveness of our algorithm.
Contractual Date of Delivery to the CEC: 31-Jul-2012 Actual Date of Delivery to the CEC: 31-Jul-2012
"... Final description and specification of cognitive manager and corresponding QoS support mechanisms with performance evaluation ..."
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Final description and specification of cognitive manager and corresponding QoS support mechanisms with performance evaluation
Coexistence of Wireless Networks for Shared Spectrum Access
, 2014
"... The radio frequency spectrum is not being efficiently utilized partly due to the current policy of allocating the frequency bands to specific services and users. In opportunistic spectrum access (OSA), the “white spaces ” that are not occupied by primary users (a.k.a. incumbent users) can be opportu ..."
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The radio frequency spectrum is not being efficiently utilized partly due to the current policy of allocating the frequency bands to specific services and users. In opportunistic spectrum access (OSA), the “white spaces ” that are not occupied by primary users (a.k.a. incumbent users) can be opportunistically utilized by secondary users. To achieve this, we need to solve two problems: (i) primary-secondary incumbent protection, i.e., prevention of harmful interference from secondary users to primary users; (ii) secondary-secondary network coexistence, i.e., mitigation of mutual interference among secondary users. The first problem has been addressed by spectrum sensing techniques in cognitive radio (CR) networks and geolocation database services in database-driven spectrum sharing. The second problem is the main focus of this dissertation. To obtain a clear picture of coexistence issues, we propose a taxonomy of heterogeneous coexistence mechanisms for shared spectrum access. Based on the taxonomy, we choose to focus on four typical coexistence scenarios in this dissertation. Firstly, we study sensing-based OSA, when secondary users are capable of employing the channel aggregation technique. However, channel aggregation is not always beneficial due to dynamic spectrum availability and limited radio capability. We propose a channel usage
