scholarly journals Fuzzy-Logic based Selection and Switching of Channels in Cognitive-Radio Networks

Author(s):  
Nikita Kanchan

In Wireless-Communication, quick increments of cell phones furthermore, the heterogeneous condition have expanded the prerequisite for extra spect-rum for information transmiss-ion. It is past the domain of imagination to allocate new bands to all networks, which is the explanation behind product-ive utilizat-ion of the adequately available spect-rum is the interest of the day. Cognitive-radio (CR) development is a promising response for compelling range use, where Cognitive-Radio devices, or optional clients (SUs), can keenly utilize void areas open in the authorized channels. Secondary-Users need to rapidly surrender the authorized channel and change to another available channel when they recognize the presence of the essential client. In any case, execution for the SU truly taints if constant channel exchanging happens. Likewise, taking the channel-turning choices subject to fresh rationale is certainly isn't sensible procedure in the brain empowered Cognitive-Radio networks (CRNs) where recognizing information isn't simply free and misguided at this point furthermore incorporates a huge vulnerability factor. We propose a Fuzzy-Logic Supportive System (FLSS) commonly oversees channel-choice and channel-changing to redesign general through-put of CRNs. Proposed plot decreases the SU channel-exchanging rate and channel-determination more adaptable. Assessment of execution is refined utilizing MATLAB Simulator. The results are promising in regards to the through-put and the num-ber of hand-offs subsequently, FLSS ends up being a fair candidate framework for SUs while making the judicious choices in Cognitive-Radio condition.


2009 ◽  
Vol 53 (8) ◽  
pp. 1158-1170 ◽  
Author(s):  
Xavier Gelabert ◽  
Ian F. Akyildiz ◽  
Oriol Sallent ◽  
Ramon Agustí


Author(s):  
Sylwia Romaszko ◽  
Petri Mähönen

In the case of Opportunistic Spectrum Access (OSA), unlicensed secondary users have only limited knowledge of channel parameters or other users' information. Spectral opportunities are asymmetric due to time and space varying channels. Owing to this inherent asymmetry and uncertainty of traffic patterns, secondary users can have trouble detecting properly the real usability of unoccupied channels and as a consequence visiting channels in such a way that they can communicate with each other in a bounded period of time. Therefore, the channel service quality, and the neighborhood discovery (NB) phase are fundamental and challenging due to the dynamics of cognitive radio networks. The authors provide an analysis of these challenges, controversies, and problems, and review the state-of-the-art literature. They show that, although recently there has been a proliferation of NB protocols, there is no optimal solution meeting all required expectations of CR users. In this chapter, the reader also finds possible solutions focusing on an asynchronous channel allocation covering a channel ranking.



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):  
Rajni Dubey ◽  
Sanjeev Sharma ◽  
Lokesh Chouhan

Most of the frequency spectrum bands have already been licensed, and the licensed spectrum is not being utilized efficiently. Cognitive Radio Networks (CRNs) are the kind of full duplex radio that automatically altered its transmission or reception parameters, in such a way that the entire wireless communication network of which it is a node communicates efficiently, while avoiding interference with primary or secondary users. In this chapter, the authors introduce the concept of security threats that may pose a serious attack in CRN. Due to the unique characteristics of CRN, such network is highly vulnerable to security attacks compared to wireless network or infrastructure-based wireless network. The main objective of this chapter is to assist CR designers and the CR application engineers to consider the security factors in the early development stage of CR techniques. Challenges and various security issues are explored with respect to OSI (Open Systems Interconnection) reference model. Various possible and attacks are discussed broadly and respective solutions are also proposed by this chapter. Different architectures and models are also explained, and compared with the existing models.



Author(s):  
Hisham M. Abdelsalam ◽  
Haitham S. Hamza ◽  
Abdoulraham M. Al-Shaar ◽  
Abdelbaset S. Hamza

Efficient utilization of open spectrum in cognitive radio networks requires appropriate allocation of idle spectrum frequency bands (not used by licensed users) among coexisting cognitive radios (secondary users) while minimizing interference among all users. This problem is referred to as the spectrum allocation or the channel assignment problem in cognitive radio networks, and is shown to be NP-hard. Accordingly, different optimization techniques based on evolutionary algorithms were needed in order to solve the channel assignment problem. This chapter investigates the use of particular swarm optimization (PSO) techniques to solve the channel assignment problem in cognitive radio networks. In particular, the authors study the definitiveness of using the native PSO algorithm and the Improved Binary PSO (IBPSO) algorithm to solve the assignment problem. In addition, the performance of these algorithms is compared to that of a fine-tuned genetic algorithm (GA) for this particular problem. Three utilization functions, namely, Mean-Reward, Max-Min-Reward, and Max-Proportional-Fair, are used to evaluate the effectiveness of three optimization algorithms. Extensive simulation results show that PSO and IBPSO algorithms outperform that fine-tuned GA. More interestingly, the native PSO algorithm outperforms both the GA and the IBPSO algorithms in terms of solution speed and quality.



2014 ◽  
Vol 5 (2) ◽  
pp. 61-74 ◽  
Author(s):  
Fatemeh Afghah ◽  
Abolfazl Razi

In this paper, a novel property-right spectrum leasing solution based on Stackelberg game is proposed for Cognitive Radio Networks (CRN), where part of the secondary users present probabilistic dishonest behavior. In this model, the Primary User (PU) as the spectrum owner allows the Secondary User (SU) to access the shared spectrum for a fraction of time in exchange for providing cooperative relaying service by the SU. A reputation based mechanism is proposed that enables the PU to monitor the cooperative behavior of the SUs and restrict its search space at each time slot to the secondary users that do not present dishonest behavior in the proceeding time slots. The proposed reputation-based solution outperforms the classical Stackelberg games from both primary and reliable secondary users' perspectives. This novel method of filtering out unreliable users increases the PU's expected utility over consecutive time slots and also encourages the SUs to follow the game rule.



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