scholarly journals A Spectrum Sensing Method for TDM based Cognitive Radio Networks

2018 ◽  
Vol 7 (4.1) ◽  
pp. 124
Author(s):  
D Satyanarayana ◽  
Abdullah Said Alkalbani

The usage of mobile radio devices has been increased exponentially for the last few years and the radio spectrum is being exhausted every day. Hence, there is huge demand for new methods and technologies for solving the radio spectrum scarcity. On this line, the researchers invented a new technology called Cognitive Radio Networks (CRN). There are two phases associated with the CRN. The first phase handles the spectrum hole detection and the second phase allocates the spectrum hole. In this paper, we propose a new method for spectrum hole detection in time division multiplexing (TDM) based communications systems. The simulation work shows that the proposed method is useful for solving the spectrum scarcity problems in TDM based systems.   

2017 ◽  
Vol 14 (3) ◽  
pp. 87-96 ◽  
Author(s):  
Jie Huang ◽  
Xiaoping Zeng ◽  
Xiaoheng Tan ◽  
Xin Jian ◽  
Yuan He

Author(s):  
Yong Yao ◽  
Alexandru Popescu ◽  
Adrian Popescu

Cognitive radio networks are a new technology based on which unlicensed users are allowed access to licensed spectrum under the condition that the interference perceived by licensed users is minimal. That means unlicensed users need to learn from environmental changes and to make appropriate decisions regarding the access to the radio channel. This is a process that can be done by unlicensed users in a cooperative or non-cooperative way. Whereas the non-cooperative algorithms are risky with regard to performance, the cooperative algorithms have the capability to provide better performance. This chapter shows a new fuzzy logic-based decision-making algorithm for channel selection. The underlying decision criterion considers statistics of licensed user channel occupancy as well as information about the competition level of unlicensed users. The theoretical studies indicate that the unlicensed users can obtain an efficient sharing of the available channels. Simulation results are reported to demonstrate the performance and effectiveness of the suggested algorithm.


Author(s):  
Shikha Singhal ◽  
Shashank Gupta ◽  
Adwitiya Sinha

The role of artificial intelligence techniques and its impact in context of cognitive radio networks has become immeasurable. Artificial intelligence redefines and empowers the decision making and logical capability of computing machines through the evolutionary process of leaning, adapting, and upgrading its knowledge bank accordingly. Significant functionalities of artificial intelligence include sensing, collaborating, learning, evolving, training, dataset, and performing tasks. Cognitive radio enables learning and evolving through contextual data perceived from its immediate surrounding. Cognitive science aims at acquiring knowledge by observing and recording externalities of environment. It allows self-programming and self-learning with added intelligence and enhanced communicational capabilities over wireless medium. Equipped with cognitive technology, the vision of artificial intelligence gets broadened towards optimizing usage of radio spectrum by accessing spectrum availability, thereby reducing channel interferences while communication among licensed and non-licensed users.


2011 ◽  
Vol 13 (14) ◽  
pp. 1247-1262 ◽  
Author(s):  
Weiwei Wang ◽  
Jun Cai ◽  
Attahiru S. Alfa ◽  
Anthony C.K. Soong ◽  
Simin Li

Author(s):  
Nitin Gupta ◽  
Sanjay Kumar Dhurandher ◽  
Bhoopendra Kumar

The radio spectrum is witnessing a major paradigm shift from fixed spectrum assignment policy to the dynamic spectrum access, which will completely change the way radio spectrum is managed. This step is required to greatly reduce the load on limited spectrum resources, which is being enforced by the exponential growth of wireless services. This is only feasible due to the capabilities of the cognitive radio, which will provide a new paradigm in wireless communication by exploiting the existing unused spectrum bands opportunistically. The chapter provides insight into recent developments in the area of cognitive radio networks with the main focus on review of the spectrum management, which consists of four main challenges: sensing of selected spectrum band, decision about sensed spectrum, sharing of spectrum among many users, and spectrum handoff. Further, sharing of target channel after a channel handoff is analyzed using game theory to get a different perspective on the existing medium access techniques.


Author(s):  
Bin Wang ◽  
Zhiqiang Wu ◽  
Zhongmei Yao

Radio spectrum has become a precious resource. Most frequency bands have been allocated for exclusive use in the US. However, studies have shown that a very large portion of the radio spectrum is unused or underused for long periods of time at a given geographic location. Therefore, allowing users without a license to operate in licensed bands while causing no interference to the license holder becomes a promising way to satisfy the fast growing need for spectrum resources. Dynamic spectrum access and cognitive radio are technologies for enabling opportunistic spectrum access and enhancing the efficiency and utilization of the spectrum. A cognitive radio adapts to the environment in which it operates by sensing the spectrum and then opportunistically exploiting unused and/or underused frequency bands in order to achieve certain performance goals. Due to the close coupling and interaction among protocol layers, the optimal design of opportunistic spectrum access and cognitive radio networks calls for a cross-layer approach that integrates signal processing and networking with regulatory policy making. This chapter introduces basic concepts, design issues involved, and some recent development in this emerging technological field. Future research directions are also briefly examined.


Author(s):  
Monisha Ravi ◽  
Nisha Ravi ◽  
N. Ravi

Recently, the expansive growth of wireless services, regulated by governmental agencies assigning spectrum to licensed users, has led to a shortage of radio spectrum. Since the FCC (Federal Communications Commissions) approved unlicensed users to access the unused channels of the reserved spectrum, new research areas seeped in, to develop Cognitive Radio Networks (CRN), in order to improve spectrum efficiency and to exploit this feature by enabling secondary users to gain from the spectrum in an opportunistic manner via optimally distributed traffic demands over the spectrum, so as to reduce the risk for monetary loss, from the unused channels. However, Cognitive Radio Networks become vulnerable to various classes of threats that decrease the bandwidth and spectrum usage efficiency. Hence, this survey deals with defining and demonstrating framework of one such attack called the Primary User Emulation Attack and suggests preventive Sensing Protocols to counteract the same. It presents a scenario of the attack and its prevention using Network Simulator-2 for the attack performances and gives an outlook on the various techniques defined to curb the anomaly.


2011 ◽  
Vol 12 (03) ◽  
pp. 155-171 ◽  
Author(s):  
SAZIA PARVIN ◽  
FAROOKH KHADEER HUSSAIN ◽  
SONG HAN ◽  
OMAR KHADEER HUSSAIN

Cognitive Radio Networks (CRNs) is a promising technology which deals with shared spectrum access and usage in order to improve the utilization of limited radio spectrum resources for future wireless communications and mobile computing. Security becomes a very challenging issue in CRNs as different types of attacks are very common to cognitive radio technology compared to general wireless networks. The proper working of cognitive radio and the functionality of CRNs relies on the compliant behaviour of the secondary user. In order to address this issue, we propose two approaches in this paper. Firstly, we propose a trust aware model to authenticate the secondary users of CRNs which offers a reliable technique to provide a security-conscious decision by using trust evaluation for CRNs. Secondly, we propose an analytical model for analyzing the availability of spectrum in CRNs using a stochastic approach. We have modeled and analyzed the availability of free spectrum for the usage of secondary users by adopting different activities in a spectrum management scheme to improve the spectrum availability in CRNs.


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