Top PDF Study and Optimization of Cooperative Spectrum Sensing in OFDM Cognitive Radio Networks

Study and Optimization of Cooperative Spectrum Sensing in OFDM Cognitive Radio Networks

Study and Optimization of Cooperative Spectrum Sensing in OFDM Cognitive Radio Networks

Orthogonal Frequency Division Multiplexing (OFDM) has become the core modulation technique solution for next generation wireless communication. It has been used by primary users (PU) due to the character of multicarrier and high spectrum efficiency. Recently the study of detection of OFDM signal in cognitive radio (CR) system has drawn considerable attention. The detection algorithms of single cognitive user can be roughly divided into two categories: the algorithm based on Pilot Tones (PT) [1] and the algorithm based on Cyclic Prefix (CP) [2-5], for the reason that the PT mode is variable and difficult to obtain through estimation, more research is focus on the algorithm based on CP. The correlation of CP has been calculated to detect the PU signal in the time of a single OFDM block in [2], and then a new algorithm was proposed by extending the correlation detection to a series of consecutive OFDM blocks in [3]. After analysis of [2,6], the Optimal NEYMAN-PEARSON Detector (ONPD) was proposed based on NEYMAN-PEARSON criterion in [4]. And this ONPD algorithm does not need any prior knowledge about synchronization information with low complexity. Through related literature analysis, we found that most
Mostrar mais

5 Ler mais

RF-Spectrum Opportunities for Cognitive Radio Networks Operating Over GSM Channels

RF-Spectrum Opportunities for Cognitive Radio Networks Operating Over GSM Channels

A few works describe the GSM spectrum availability at specific locations. Reference [7] evaluates the GSM spectrum availability at Jaipur city, India, describing the experimental measurement setup and the analysis procedure followed in the study. The work identifies multiple spectrum spaces which can support potential CR applications. The authors used a spectrum analyzer in the GSM band to determine the aver- age power spectral density. Similarly, [8] also identifies and characterizes the channel opportunities over a GSM network in Aveiro, Portugal. The results have showed that RF-spectrum opportunities over GSM licensed frequencies follow an expo- nential behavior. Similar results were observed in [9] and [10]. Patil et al. [11] characterize the temporal opportunities through detailed measurements obtained in GSM channels, includ- ing statistical as well as spectral occupancy details. However, the works in [4], [5], and [8]–[11] focused mostly on characterizing the transmission opportunities over the GSM licensed bands and do not address the theoretical charac- terization of the service time when using the transmission opportunities.
Mostrar mais

9 Ler mais

Spectrum Sensing Methodologies for Cognitive Radio Systems: A Review

Spectrum Sensing Methodologies for Cognitive Radio Systems: A Review

design. Selection of sensing parameters brings about tradeoff between the speeds (sensing time) and reliability of sensing. Sensing frequency is a design parameter that needs to be chosen carefully [23]. In a case when the status of primary users is known to change slowly, sensing frequency requirements can be relaxed. In addition to sensing frequency, the channel detection time, channel move time and some other timing related parameters are also defined in [24]. Another factor that can affect the sensing frequency is the interference tolerance of primary license owners. An example is when a cognitive radio is using opportunities in public safety bands, sensing should be done as frequently as possible in order to prevent any interference. The effect of sensing time on the performance of secondary users is investigated in [25].The aim is to maximize the average throughput of secondary users while guiding primary users from interference [18]. Similarly, detection time is obtained using numerical optimization in [26]. Channel efficiency is maximized for a given detection probability. Sensing time can be decreased by sensing only changing parts of the spectrum instead of the entire target. A channel that is being used by secondary users cannot be used for sensing. Hence, secondary users have to stop data transmission for spectrum sensing [27]. This however, decreases the spectrum efficiency of the overall system [23]. To solve this problem, a method known as dynamic frequency hopping (DFH) is proposed. The DFH method is based on the assumption of having more than a single channel. This was proposed in [28].
Mostrar mais

10 Ler mais

A Novel Reservation-based MAC Scheme for Distributed Cognitive Radio Networks

A Novel Reservation-based MAC Scheme for Distributed Cognitive Radio Networks

are used to synchronization and channel access (transmission). Initially, an SU assumes the synchronization task if it does not receive synchronization information during a predefined time interval. Such an SU is called synchronizer and is responsible for the transmission of a short synchronization packet during the ϕ interval containing the duration of the spectrum sens- ing and spectrum access periods. The synchronization (SYNC) packet is transmitted by the synchronizer whenever the chan- nel is sensed idle during the spectrum sensing period. By re- ceiving the SYNC packet, the neighbors (denoted as followers) know the duration of the spectrum sensing and spectrum ac- cess periods and may correct clock drifts. If the synchronizer SU does not transmit the SYNC packet within a given period of time denoted as SYNC_TIMEOUT (e.g., because that SU has finished its activity), any follower may then assume that role. To become a synchronizer, a follower is allowed to ran- domly transmit the SYNC packet after the SYNC_TIMEOUT has been elapsed. Randomness is used to avoid multiple nodes acting simultaneously as synchronizers. This is similar to the synchronization schemes already proposed for distributed MAC schemes of wireless sensor networks, where any node can act as a synchronizer [30]. For the sake of simplicity of the anal- ysis, in what follows, we consider that the SU Rx is always a synchronizer, being responsible for the synchronization of
Mostrar mais

5 Ler mais

Routing in Cognitive Radio Networks - A Survey

Routing in Cognitive Radio Networks - A Survey

As with less hop distance in which nodes have long transmission range, can lead to more SU interference and performance decreases due to more link failures. So hop count along with spectrum awareness is necessary to improve end to end delay. During transmission, channel unavailability at a single node leads to link breakage is a serious issue to be solved when end to end delay is considered. There are many well defined procedures proposed to avoid rerouting which is very costly as it increases end to end delay. Channels available at different nodes are of different bandwidth, propagation characteristics and available for unequal times due to channel heterogeneity. [63]. A cross layer framework is proposed for spectrum assignment and routing [64]. Backup channel mechanism enables cooperative channel switching which proves to be an efficient solution for minimizing the end to end delay and the problems created due to channel heterogeneity [69].Neighboring nodes can switch to a single channel in a cooperative manner. This enables a transmitting node to find the same set of neighbors on a different channel with the condition that the neighbors can also tune to the same secondary channel.
Mostrar mais

13 Ler mais

User Characterization through Dynamic Bayesian Networks in Cognitive Radio Wireless Networks

User Characterization through Dynamic Bayesian Networks in Cognitive Radio Wireless Networks

Cognitive Radio is a technology that allows to implement new and innovative skills to wireless systems such as dynamic access to spectrum; a concept comprising the autonomous control of multiple variables such as sensing, decision making, sharing and spectral mobility within the system. To include these skills in CR, researchers have proposed the use of some artificial intelligence techniques in each of the stages comprised in the concept of CR. One of the methodologies that has had less acceptance and could be an important reference for application in the dynamic spectrum access is known as Bayesian networks, the focus of our proposal to improve the percentage of modeling and characterization of PUs in the spectral decision making stage from spectrum sensing.
Mostrar mais

13 Ler mais

ENERGY DETECTION BASED SPECTRUM SENSING FOR COGNITIVE RADIO

ENERGY DETECTION BASED SPECTRUM SENSING FOR COGNITIVE RADIO

CR is an persuasive resolution to the spectral congestion crisis by establishing the opportunistic exploitation of unused frequency bands that are not significantly engaged through a licensed users. They cannot be utilized by users other than the license CR users at the moment. OFDM is one of the most extensively used technologies in recent wireless communication systems which has the latent of satisfying the necessities of cognitive radios intrinsically or with minor changes. With it interoperability among the different protocols, it becomes easier.
Mostrar mais

5 Ler mais

Channel Decision in Cognitive Radio Enabled Sensor Networks: A Reinforcement Learning Approach

Channel Decision in Cognitive Radio Enabled Sensor Networks: A Reinforcement Learning Approach

Authors in [6] proposed a novel biologically inspired consensus-based cooperative spectrum sensing scheme for cognitive radio mobile ad hoc networks (CR-MANETs). Decision making in this scheme is without the use of common receiver for data aggregation. This is only applicable to distributed network. Centralized cluster- based CR-aided sensor network cannot adapt this scheme. Bothered by interference problem, [7] proposed a systematic framework to produce conflict graphs based on physical interference characteristics. This framework optimizes conflict graph in order to produce spectrum allocations that match those derived from physical interference model. In [8] the authors considered CR system with one SU accessing multiple channels using periodic sensing and channel switching. Optimal spectrum sensing and access mechanism was proposed with focus on energy minimization in the presence of multi-constraints-sensing reliability, throughput and delay in the SU transmission. To minimize interference to PU and to maximize channel utilization [9] proposed a framework of constrained Markov decision processed, and optimal access policy based on linear program. Similar to previous work in [6], authors in [10] considered decentralized spectrum access using the theory of multivariate global game. Channel access is based on Bayesian estimate of the intention of the other SUs and based on expected throughput of the SU under consideration. Authors in [11] applied reinforcement learning to develop a new routing algorithm based on continuous link model. In the work, the idea of Q-learning was transferred into link-value. From the results obtained, it was shown that the reinforcement learning based algorithm gave improved performance in terms of link table and packet delivery ratio in ad hoc networks compared to AODV and DSR.
Mostrar mais

11 Ler mais

Mitigating Intrusion and Vulnerabilities in Cognitive Radio Networks

Mitigating Intrusion and Vulnerabilities in Cognitive Radio Networks

The security threats in cognitive radio entail majorly illegal information injection and forging of information transmission. The radio environment map (REM) fetches several characteristic data from a large spectrum sensing cognitive users. Attackers can maliciously falsify local spectrum sensing data to confuse the receiver in other to lunch attacks which can prompt the receiver to make wrong spectrum accessing decision [8]. A secure computer network is a trusted and reliable system that functions appropriately. Normally, information technology security is usually analyzed on the basics of confidentiality, integrity and availability. In the 1980s, computer systems had been equipped already with an audit capability. The operating system can be able to collect system-wide attributes using the audit trace capability. The analysis been done by humans became very tedious as collected events and activities increased. An automated method of collecting and analyzing data to produce vital information to check network intrusions became very necessary. However, the birth of this automated mechanism or tool became the foundation or root of intrusion detection.
Mostrar mais

10 Ler mais

Current Trends and Research Challenges in Spectrum-Sensing for Cognitive Radios

Current Trends and Research Challenges in Spectrum-Sensing for Cognitive Radios

Rashid in [22] proposed a fast-convergence particle swarm optimization (FC-PSO) scheme. It is fine sensing scheme to find a trade-off between sensing time and throughput. The parameters considered in the study are detection performance, optimization time, and SU gain. The paper utilized energy detection scheme for in-band spectrum sensing. Detection performance, optimization time, and SU gain are some of the key parameters considered in this paper. A trade-off problem was formulated between the stopping threshold, sensing performance and the optimization time. Traditionally, the stopping criterion was based on measurement of error or limiting the maximum number of iterations. However, FC- PCO algorithm imposed a limit rule to stop the evaluation. When a certain number of particles reach a global optimum, the algorithm stopped. This is based on the fact that the remaining particles will not produce any new information and will be a waste of computational resources.
Mostrar mais

7 Ler mais

Analytical Model Analysis Of Distributed Cooperative Spectrum Sensing Method

Analytical Model Analysis Of Distributed Cooperative Spectrum Sensing Method

This section relates to spectrum sensing control, awareness networking and cooperative spectrum sensing in Figure 1. Cooperative spectrum sensing is a powerful concept to leverage the spatial separation of multiple spectrum sensing nodes in a wireless network. The optimal fusion of sensing results, acquired by distributed network nodes, allows to alleviate the hidden node problem and/or to share the sensing load between network nodes. The optimal fusion of decentralized observations has been studied since a long time, see e.g., [20] and the references therein. It has been shown already in [8], [9] that the optimal fusion rule is to compute the joint likelihood ratio of the distributed observations. Cooperative spectrum sensing requires a networking solution to communicate sensing results (sensing messages) between nodes. Using spectrum sensing individual network nodes, as well as the whole network by virtue of collaboration, becomes aware of the local radio spectrum situation. Consequently the distribution of spectrum sensing results can be understood as Awareness Signaling. Within E3 (End-to-End Efficiency project) an awareness signaling solution, namely Cognitive Control Radio (CCR) has been developed [10], [11].
Mostrar mais

4 Ler mais

Performance analysis of partial relay selection in cooperative spectrum sharing systems

Performance analysis of partial relay selection in cooperative spectrum sharing systems

Sonia Aïssa received her Ph.D. degree in Electrical and Computer Engineering from McGill University, Montreal, QC, Canada, in 1998. Since then, she has been with the National Institute of Scientific Research-Energy, Materials, and Telecommunications (INRS-EMT), University of Quebec, Montreal, QC, Canada, where she is a Profes- sor. From 1996 to 1997, she was a Researcher with the Department of Electronics and Communications of Kyoto University, Kyoto, Japan, and with the Wireless Systems Laboratories of NTT, Kanagawa, Japan. From 1998 to 2000, she was a Research Associate at INRS-EMT, Mon- treal. From 2000 to 2002, while she was an Assistant Professor, she was a Principal Investigator in the major program of personal and mobile communications of the Canadian Institute for Telecommunica- tions Research (CITR), leading research in radio resource management for code division multiple access systems. From 2004 to 2007, she was an Adjunct Professor with Concordia University, Montreal. In 2006, she was Visiting Invited Professor with the Graduate School of Infor- matics, Kyoto University, Japan. Her research interests lie in the area of wireless and mobile communications, and include radio resource management, cross-layer design and opti- mization, design and analysis of multiple antenna (MIMO) systems, cognitive and cooperative transmission techniques, and performance evaluation, with a focus on Cellular, Ad Hoc, and Cognitive Radio networks. Dr. Aïssa was the Founding Chair of the Montreal Chapter IEEE Women in Engineering Society in 2004– 2007, acted or is currently acting as Technical Program Leading Chair or Cochair for the Wireless Com- munications Symposium of the IEEE International Conference on Communications (ICC) in 2006, 2009, 2011 and 2012, as PHY/MAC Program Chair for the 2007 IEEE Wireless Communications and Networking Conference (WCNC), and as Technical Program Committee Cochair of the 2013 IEEE Vehicular Technol- ogy Conference – spring (VTC). She has
Mostrar mais

14 Ler mais

A Cooperative Spectrum Sensing Scheme Based on Trust and Fuzzy Logic for Cognitive Radio Sensor Networks

A Cooperative Spectrum Sensing Scheme Based on Trust and Fuzzy Logic for Cognitive Radio Sensor Networks

To evaluate the performance of the proposed cooperative spectrum sensing algorithm for CRSN and compare the performance with some exiting methods, the Monte-Carlo simulations are carried out with 100,000 samples under the following conditions: The number of CRSN nodes

5 Ler mais

ENERGY EFFICIENT COOPERATIVE SPECTRUM SENSING IN COGNITIVE RADIO

ENERGY EFFICIENT COOPERATIVE SPECTRUM SENSING IN COGNITIVE RADIO

Spectrum sensing is a continuous stage during the life cycle of cognitive radio communications where it must be done initially to find an idle channel and then must be done periodically to protect the PU, where if the PU is active again, sensing is used to find another idle channel. Therefore, reducing sensing time increases the room left for transmission which achieves the main target of CR of increasing wireless spectrum utilization. Moreover, sensing plays a crucial role in the success of the whole process, where the use of PU’s channel is under the constraint that the PU is protected. PU protection is achieved by sensing. For this reason, sensing has received a lot of attention in order to perform it efficiently.
Mostrar mais

12 Ler mais

SPECTRUM SENSING IN COGNITIVE RADIO NETWORKS: QOS CONSIDERATIONS

SPECTRUM SENSING IN COGNITIVE RADIO NETWORKS: QOS CONSIDERATIONS

In some environments, cooperative sensing may lose its advantages as far as an individual SU is concerned. For instance, increasing the local sensing frequency in individual high mobility SUs is more efficient, in terms of sensing accuracy and overhead, than to cooperate with other SUs [19]. In cooperative sensing, the improvement of sensing is more noticeable when the number of cooperative SUs is increased. However, involvement of more SUs will increase the cooperation overhead in terms of the amount of data exchange and the time required for the exchange [32]. The cooperative approaches can only be used when SUs are able and willing to collaborate. Also, a SU may not always find other cooperative SUs within its transmission range. Therefore, the CR devices should not solely rely on cooperative sensing approaches. They should be able to use a fitting local sensing method and resort to cooperative sensing, only when an enhanced performance is possible.
Mostrar mais

11 Ler mais

Overhead Reduction in Cooperative Spectrum Sensing Via Sequential Detection in Cognitive Radio Networks Under Bandwidth Constraint

Overhead Reduction in Cooperative Spectrum Sensing Via Sequential Detection in Cognitive Radio Networks Under Bandwidth Constraint

R eliable and efficient spectrum sensing plays an important role in cognitive radio networks. On the other hand, accurate and fast sensing of spectrum is the main function of a cognitive radio for cognitive users to avoid harmful interference in licensed users. However, detection performance issues are often shadowing, fading and receiver uncertainty. To mitigate the impact of these issues, cooperative spectrum sensing as an effective method is presented to improve the detection performance with help of spatial diversity. Cooperative spectrum sensing leads to CR detection performance improvement. In order to execute the cooperative spectrum sensing among cognitive radio users, data fusion schemes are superior to that of decision fusion ones in terms of the detection performance but suffer from the disadvantage of huge traffic overhead when bandwidth constraint of communication channels is taken into account. The overhead contains additional sensing time, delay, energy and sensing actions dedicated to cooperative sequential sensing any also contains any performance degradation that is caused by cooperative sensing. The purpose of this paper is reviewing of the cooperative sensing techniques with sequential methods. The simulation results show that with reducing the number of examined samples, the sensing time and the energy will be reduced and as the result, the overhead will be reduced. Index Terms: Cognitive radio, sequential spectrum sensing, cooperative sensing, overhead, hard decision.
Mostrar mais

6 Ler mais

Planning and dynamic spectrum management in heterogeneous mobile networks with QoE optimization

Planning and dynamic spectrum management in heterogeneous mobile networks with QoE optimization

To study the performance of the proposed iCRRM, several LTE system level simulations have been performed within a LTE-A scenario. The comparison parameters include the average cell supported goodput, delay, Packet Loss Ratio (PLR) and spectral efficiency. The LTE simulator chosen to perform this evaluation is LTE-Sim [135], developed at the University of Bari. LTE-Sim is an event-driven simulator, written in C++, using the object-oriented paradigm. Several traffic generators at the application layer have been implemented and the management of data radio bearer is supported. In particular, the video traffic addressed in this research is a trace-based application which sends packets based on realistic video trace files. To study the performance of the proposed iCRRM the inter-band CA scenario shown in Figure 6.4 is considered. UEs are constantly moving at 3 kmph using LTE- Sim random direction mobility model, each UEs only use one H.264 128 kbps video bit rate flow, and maximum delay of 1 ms is considered. LTE-Sim [135] provides a support for radio resource allocation in a time – frequency domain and, in this configuration, the duration of one LTE radio frame is 10 ms. One frame is divided into 10 sub-frames of 1 ms each, and each sub-frame is divided into two slots of 0.5 ms each. Each slot contains either six or seven OFDM symbols, depending on the Cyclic Prefix (CP) length [137]. The normal CP is used in urban cells and high data rate applications while the extended CP is used in special cases like multi- cell broadcast and in very large cells (e.g., rural areas, low data rate applications).
Mostrar mais

215 Ler mais

Intelligent Wireless Communication System Using Cognitive Radio

Intelligent Wireless Communication System Using Cognitive Radio

Most research related to the QoS of video conferencing, take into account throughput as pertinent parameter. For this reason, we choose the “Throughput” as a single pertinent parameter for our application. For this, a throughput classification is required, and as we play the role of the expert, we have created our own database following certain rules in order to apply our approach. The database was divided into two parts, the first one for learning and the second one for testing. The value of the throughput will change almost every time it is measured during the day even on the same route, for this reason, our measures have been taken into account for 5 weeks at 3 different intervals of the day (8am – 11am, 11am – 3pm, 3pm – 5pm) excluding weekend.
Mostrar mais

14 Ler mais

A decoding method of an n length binary BCH code through (n + 1)n length binary cyclic code

A decoding method of an n length binary BCH code through (n + 1)n length binary cyclic code

TARIQ SHAH 1 , MUBASHAR KHAN 1 and ANTONIO A. DE ANDRADE 2 1 Department of Mathematics, Quaid-i-Azam University, 45320, Islamabad, Pakistan 2 Departamento de Matemática, IBILCE, Universidade Estadual Paulista “Júlio de Mesquita Filho”, Rua Cristóvão Colombo, 2265, Bairro Jardim Nazareth, 15054-000 São José do Rio Preto, SP, Brasil

10 Ler mais

Video Transmission over Cognitive Radio TDMA Networks under Collision Errors

Video Transmission over Cognitive Radio TDMA Networks under Collision Errors

In this paper, we consider scalable video transmission over Cognitive Radio networks. The primary network has a binomial-modeled traffic. We have suggested making use of a progressive source coding associated to a fountain code. Then, we have evaluated the impact of the primary traffic interruptions on the secondary traffic and used a general model for collisions to modelize the opportunistic access of secondary users to CR network. Further, we have exploited a simple duplication-based mechanism for SULs to ameliorate the Goodput of the video transmission and make the SUs concurrency more infrequent. Our numerical results have been presented in terms of computed Goodput of the system. The achieved gain, while increasing the SULs number, proves the effectiveness of the given solution in terms of QoS requirements for video communication in secondary use. The paper concludes by emphasizing the importance of finding a balance that meets expected quality and achieved Goodput of the system. Hence, our video transmission parameters should be carefully chosen.
Mostrar mais

9 Ler mais

Show all 10000 documents...