Cognitive radio is an innovative technology in the field of wireless communication systems, aimed at significantly improving the use of the radio spectrum while allowing secondary users to access the spectral band opportunistically. Spectrum management mechanism ensures the transmission of data by controlling the efficiency of operation between the primary and secondary networks. The main task of spectrum management is to ensure that secondary users benefit from the spectrum without interfering with primary users. This paper deals with some of the important characteristics of spectrum mobility in the cognitive radio networks. The new management approaches of the mobility and the connection are designed to reduce the latency and loss of information during spectrum handoff, a list of channel safeguard is maintained in this effect, but the maintenance and update are a challenge. In this paper, we describe the reasons and mechanisms of spectrum handoff. Protocols have been developed to illustrate this handoff mechanism. We also make a comparison between the different methods of spectrum handoff. The simulation results obtained confirm that the protocols developed and the proposed method performed better than the pure reactive handoff method.

Fog computing extends cloud computing, provides the services like data, compute, storage and application to end user. It improves the quality of service and also reduces latency. According to Cisco, due to its wide geographical distribution, the Fog computing is well suited for real time analytics and big data. This article, by exploitation advantages of Fog computing Paradigm, analyzes its applications in a series of real scenarios, such as Smart Grid, smart traffic lights in vehicular networks, Wireless Sensor and Actuator Networks, Decentralized Smart Building Control, IoT and Cyber-physical systems and software defined networks, and reviews Comprehensive Approach for security Data Theft Attack the use of Elliptic Curve Cryptography (ECC) and decoy technology in such a constrained environment along with the other two aspects of ECC, namely its security and efficiency. In the article, the performance of ECC is compared with the other PKC applications which should prove that ECC performs well and is more suitable for Fog environments.

The spectrum detection (SD) is a critical step in cognitive radio (CR) to identify the available spectrum and avoid interference and harm to primary users (PUs). Nonetheless, the practical detection process is often compromised with problems of receptors uncertainty, shadows, and multipath fading. To overcome these problems, a cooperative SD scheme is proposed by exploiting the system multiantenna (MUA) with the multiuser diversity (MUD). The SD gives unlicensed secondary users (SUs) the opportunity to use the licensed spectral band until the PU makes its appearance. By allowing the cooperation between the SUs of the same spectral band, the time of the detection is reduced and increases the general dexterity, which is the strong point of cooperative SD. In this paper, we proposed an SD scheme using a new MUA design. The scheme proposed is a clear difference compared to other systems because in this design weight of quantification is multiplied by each receiving antenna. The scheme has the ability to detect low-level signals to facilitate sharing between the SU and PU system. The numerical results are made to prove the performance of the proposed system compared to the conventional system. The results obtained confirm the efficiency of the proposed scheme.

In recent years, there has been a rapid evolution of wireless technologies that has led to the challenge of high demand for spectral resources. To overcome this challenge, good spectrum management is required that calls for more efficient use of the spectrum. In this paper, we present a general system, which makes a tradeoff between the spectral efficiency (SE) and energy efficiency (EE) in the cellular cognitive radio networks (CCRN) with their respective limits. We have analyzed the system taking into account the different types of power used in the CCRN, namely the spectrum detection power (Zs) and the relay power (Zr). Optimal policy for emission power allocation formulated in the function of sub-channel activity index (SAI) as an optimization problem in order to maximize spectrum utilization and minimize the energy consumption in the base station of the secondary system energy consumption, is subject to different constraints of the main user system. We also evaluate the collaborative activity index of the sub-channel describing the activity of the primary users in the CCRN. The theoretical analyses and simulation results sufficiently demonstrate that the SE and EE relationship in the CCRN is not contrary and thus the achievement of optimal tradeoff between SE and EE. By making a rapprochement with a cognitive cellular network where SBSs adopts an equal power allocation strategy for sub-channels, the results of our proposed scheme indicate a significant improvement. Therefore, the model proposed in this paper offers a better tradeoff between SE and EE.

Cognitive radio appears as an innovative technology in the field of access to wireless systems, aimed at significantly improving the use of the radio spectrum by allowing an opportunistic access manner. This article deals with some of the important characteristics of the spectrum mobility in cognitive radio networks (CRNs).The new management approach to the mobility and the connection are designed to reduce the latency and loss of information during spectrum handoff. A list of channel safeguards are maintained in this effect, but the maintenance and updates are a challenge. In this article, the authors describe the reasons and mechanisms for spectrum handoff. Algorithms have been developed to illustrate this handoff mechanism and make the comparison between the different methods of spectrum handoff. The simulation results obtained confirm that the proposed method and the algorithms developed presents a better performance.