Energy detection based cooperative spectrum sensing system for emergency networks

During emergencies, a number of rescue teams come to the field and setup their own radio communication systems. If the deployed communication setup does not coordinate among themselves properly, they may interfere with each other when using the same RF channels known as co-channel interference. Spectrum sensing is the most important and complex job for cognitive radios. Cooperation among cognitive radio nodes is needed to enhance the sensing performance. In this paper, we present an experimental study of this solution. A Software Defined Radio comprising of GNU Radio and USRP were used to capture the signal samples to build a database profile of the spectrum condition. MATLAB communications toolbox was used to analyze the data and examine the spectrum pertaining to the condition in emergency networks. The benefits of cooperative spectrum sensing in avoiding co-channel interference during emergency situations are illustrated. Cooperation among cognitive spectrum sensing nodes operating at the same frequency improves the probability of detection, and the overall efficiency of the system. Results show that the cooperative sensing scheme outperforms the individual sensing approach. It can increases the probability of detection relative to the collected samples as the key performance indicator

A Review paper based on spectrum sensing techniques in Cognitive Radio Networks

Natural frequency spectrum is scared resource; the efficient use of it can only accommodate the need of future computing world. But efficient use of it is not possible within the existing system, where the allocation of spectrum is done based on fixed spectrum access (FSA) policy. Many survey shows that it leads to under use of spectrum. For efficient utilization of spectrum innovative techniques is needed. using Dynamic spectrum access (DSA) policy we can exploiting the available spectrum, For given purpose Cognitive radio arises to be a tempting solution to the spectral congestion problem by introducing opportunistic usage of the frequency bands that are not heavily occupied by licensed users. This paper presents the study of different spectrum sensing techniques of cognitive radio networks. As we know Cognitive radio is a form of wireless communication where radio transceiver intelligently detects which spectrums are free which are not. After this it occupies the vacant one while avoiding busy one spectrum. Cognitive radios promote open spectrum allocation which is a clear departure from traditional command and control allocation schemes for radio spectrum usage. In short, they allow the formation of “infrastructure-less” collaborative network clusters—cognitive radio networks. However, how to detect free spectrum we have to use the spectrum sensing techniques, here we are describing all the spectrum sensing techniques and Finally concluded that cooperative sensing is better than Non-Cooperative sensing for primary user (PU) signal with  low SNR value. Keywords- CRN, FSA, PU, DSA, SU, SNR.

MULTI USER COOPERATION SPECTRUM SENSING IN WIRELESS COGNITIVE RADIO NETWORKS

With the rapid proliferation of new wireless communication devices and services, the demand for the radio spectrum is increasing at a rapid rate, which leads to making the spectrum more and more crowded. The limited available spectrum and the inefficiency in the spectrum usage have led to the emergence of cognitive radio (CR) and dynamic spectrum access (DSA) technologies, which enable future wireless communication systems to exploit the empty spectrum in an opportunistic manner. To do so, future wireless devices should be aware of their surrounding radio environment in order to adapt their operating parameters according to the real-time conditions of the radio environment. From this viewpoint, spectrum sensing is becoming increasingly important to new and future wireless communication systems, which is designed to monitor the usage of the radio spectrum and reliably identify the unused bands to enable wireless devices to switch from one vacant band to another, thereby achieving flexible, reliable, and efficient spectrum utilisation. This thesis focuses on issues related to local and cooperative spectrum sensing for CR networks, which need to be resolved. These include the problems of noise uncertainty and detection in low signal to noise ratio (SNR) environments in individual spectrum sensing. In addition to issues of energy consumption, sensing delay and reporting error in cooperative spectrum sensing. In this thesis, we investigate how to improve spectrum sensing algorithms to increase their detection performance and achieving energy efficiency. To this end, first, we propose a new spectrum sensing algorithm based on energy detection that increases the reliability of individual spectrum sensing. In spite of the fact that the energy detection is still the most common detection mechanism for spectrum sensing due to its simplicity. Energy detection does not require any prior knowledge of primary signals, but has the drawbacks of threshold selection, and poor performance due to noise uncertainty especially at low SNR. Therefore, a new adaptive optimal energy detection algorithm (AOED) is presented in this thesis. In comparison with the existing energy detection schemes the detection performance achieved through AOED algorithm is higher. Secondly, as cooperative spectrum sensing (CSS) can give further improvement in the detection reliability, the AOED algorithm is extended to cooperative sensing; in which multiple cognitive users collaborate to detect the primary transmission. The new combined approach (AOED and CSS) is shown to be more reliable detection than the individual detection scheme, where the hidden terminal problem can be mitigated. Furthermore, an optimal fusion strategy for hard-fusion based cognitive radio networks is presented, which optimises sensing performance. Thirdly, the need for denser deployment of base stations to satisfy the estimated high traffic demand in future wireless networks leads to a significant increase in energy consumption. Moreover, in large-scale cognitive radio networks some of cooperative devices may be located far away from the fusion centre, which causes an increase in the error rate of reporting channel, and thus deteriorating the performance of cooperative spectrum sensing. To overcome these problems, a new multi-hop cluster based cooperative spectrum sensing (MHCCSS) scheme is proposed, where only cluster heads are allowed to send their cluster results to the fusion centre via successive cluster heads, based on higher SNR of communication channel between cluster heads. Furthermore, in decentralised CSS as in cognitive radio Ad Hoc networks (CRAHNs), where there is no fusion centre, each cognitive user performs the local spectrum sensing and shares the sensing information with its neighbours and then makes its decision on the spectrum availability based on its own sensing information and the neighbours’ information. However, cooperation between cognitive users consumes significant energy due to heavy communications. In addition to this, each CR user has asynchronous sensing and transmission schedules which add new challenges in implementing CSS in CRAHNs. In this thesis, a new multi-hop cluster based CSS scheme has been proposed for CRAHNs, which can enhance the cooperative sensing performance and reduce the energy consumption compared with other conventional decentralised cooperative spectrum sensing modes

On achieving network throughput demand in cognitive radio-based home area networks

The growing number of wireless devices for in-house use is causing a more intense use of the spectrum to satisfy the required quality-of-service such as throughput. This has contributed to spectrum scarcity and interference problems particularly in home area networks (HAN). Cognitive radio (CR) has been recognized as one of the most important technologies which could solve these problems and sustainably meeting the required communication demands by intelligently exploiting temporarily unused spectrum, including licensed spectrum. In this paper, we propose a throughput demand-based cognitive radio solution for home area networks (TD-CRHAN) which aims at effectively and efficiently meet the ever-increasing throughput demand in HAN communication. It is shown numerically and by simulations that a TD-CRHAN can satisfy the requested throughput from the network devices and has high utilization of the available throughput. The analysis further shows that, by setting the achievable throughput to be as close as possible to the total demanded throughput (instead of maximizing it), a TD-CRHAN is able to relax the tight cooperative spectrum sensing requirements which significantly improves cooperative spectrum sensing parameters, such as the local spectrum sensing time and the number of cooperative spectrum sensing devices. Finally, it is shown that these cooperative spectrum sensing parameters can be further improved when additional channels are available

Autonomous functionalities for cognitive radio

This paper provides an overview on the research activities in autonomous functionalities for cognitive radio and networks, carried out in FP7/E3-project. The identified main research areas within this topic include opportunistic spectrum access and autonomous self-x functionalities for communication nodes. Opportunistic spectrum access delineates innovative topics concerning distributed cooperative spectrum sensing, collaborative MAC algorithms, distributed radio resource management algorithms, and control mechanisms for the opportunistic spectrum access. In autonomous self-x functionalities the research covers cognitive device management, autonomous RAT and operator selection and self-x features for autonomous elements, including autonomous decision making functionalities for RAT protocol configuration, negotiation on missing RAT protocol components, and functionality for dynamic configuration of RAT protocol components.Postprint (published version

A Stochastic based Physical Layer Security in Cognitive Radio Networks: Cognitive Relay to Fusion Center

© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Cognitive radio networks (CRNs) are found to be, without difficulty wide-open to external malicious threats. Secure communication is an important prerequisite for forthcoming fifth-generation (5G) systems, and CRs are not exempt. A framework for developing the accomplishable benefits of physical layer security (PLS) in an amplify-andforward cooperative spectrum sensing (AF-CSS) in a cognitive radio network (CRN) using a stochastic geometry is proposed. In the CRN the spectrum sensing data from secondary users (SU) are collected by a fusion center (FC) with the assistance of access points (AP) as cognitive relays, and when malicious eavesdropping SU are listening. In this paper we focus on the secure transmission of active APs relaying their spectrum sensing data to the FC. Closed expressions for the average secrecy rate are presented. Analytical formulations and results substantiate our analysis and demonstrate that multiple antennas at the APs is capable of improving the security of an AF-CSSCRN. The obtained numerical results also show that increasing the number of FCs, leads to an increase in the secrecy rate between the AP and its correlated FC

Spectrum Sensing in the Presence of Multiple Primary Users

We consider multi-antenna cooperative spectrum sensing in cognitive radio networks, when there may be multiple primary users. A detector based on the spherical test is analyzed in such a scenario. Based on the moments of the distributions involved, simple and accurate analytical formulae for the key performance metrics of the detector are derived. The false alarm and the detection probabilities, as well as the detection threshold and Receiver Operation Characteristics are available in closed form. Simulations are provided to verify the accuracy of the derived results, and to compare with other detectors in realistic sensing scenarios.Comment: Accepted in IEEE Transactions on Communication

Primary user emulation attack mitigation in cognitive radio networks.

M. Sc. Eng. University of KwaZulu-Natal, Durban 2014.The rapid progress in the number of users and applications in wireless communication have led to the problem of growing spectrum scarcity in recent years. This imminent spectrum scarcity problem is in part due to a rapidly increasing demand for wireless services and in part due to the inefficient usage of currently licensed spectrum bands. Cognitive radio (CR) is a new technology that is proposed to improve spectrum efficiency by allowing unlicensed secondary users to access the licensed frequency bands without interfering with the licensed primary users. A malicious secondary user can decide to exploit this spectrum access etiquette by mimicking the spectral characteristics of a primary user, and gain priority access to a wireless channel over other secondary users. This scenario is referred to in literature as Primary User Emulation Attack (PUEA). Though quite a lot of research efforts have been focused on the detection and defense strategy of PUEA in cognitive radio networks, less attention have been given to combating and mitigating PUEA in a cooperative spectrum sensing environment. This dissertation seeks to contribute to research in the field of cognitive radio networks through an investigation into the impacts of Primary User Emulation Attacks (PUEA) on cognitive radio networks, the problem of trust amongst users in the networks and also mitigating the activities of PUEA in the network. An analytical and system model for PUEA in cognitive radio networks is presented and its impacts are also studied using Neyman-Pearson Composite Hypothesis Test. The intention is to evict malicious users from the network and maximize spectrum utilization efficiency. To achieve this, techniques to verify that the source of spectrum occupancy information is from a genuine user are proposed. In a primary user emulation attack, malicious users tend to destruct the spectrum sensing process of a cognitive radio network by imitating the primary signal and deceive other secondary users from accessing vacant frequency bands. An energy detection cooperative spectrum sensing technique is proposed to mitigate this attack. This technique assists in the reduction of errors made by secondary users in detecting primary user signals in frequency bands considering the existence of PUEA in the network. The performance of our proposed method is compared to an existing energy detection spectrum sensing method that does not consider the existence of PUEA in the network. Simulated results show that the proposed method can effectively mitigate PUEA in a cognitive radio network