In cognitive radio network, secondary (unlicensed) users (SUs) are allowed to utilize the licensed spectrum when it is not used by the primary (licensed) users (PUs). Because of the dynamic nature of cognitive radio network, the activities of SUs such as “how long to sense” and “how long to transmit” significantly affect both the service quality of the cognitive radio networks and protection to...

In this paper, we investigate an optimization of threshold level with energy detection to improve the spectrum sensing performance. Determining threshold level to minimize spectrum sensing error both reduces collision probability with primary user and enhances usage level of vacant spectrum, resulting in improving total spectrum efficiency. However, when determining threshold level, spectrum se...

Due to that the Ultra Wide Band (UWB) technology has some attractive features like robustness to multipath fading, high data rate, low cost and low power consumption, it is widely use to implement cognitive radio network. Intuitively, one of the most important tasks required for cognitive network is the spectrum sensing. A framework for implementing spectrum sensing for UWB-Cognitive Network wi...

Relay attacks pose a significant threat against communicating devices that are required to operate within a short-distance from each other and a restricted time frame. In the field of smart cards, distance bounding protocols have been proposed as an effective countermeasure, whereas, in the field of smartphones, many proposals suggest the use of (natural) ambient sensing as an effective alterna...

Spectrum sensing plays a major role in the cognitive radio networks. An effective spectrum sensing has two fold utility: one hand it prevents primary users or licensed users for significant harmful interference from secondary users or unlicensed users and on the other hand it increases the spectral efficiency. In this paper, a survey of the various spectrum sensing schemes such as transmitter s...

Spectrum sensing is one of the most important tasks of each cognitive radio network. Cooperation among secondary users, by increasing the sensing accuracy can improve the network throughput, but also increases the energy consumption of cognitive radio network. In this paper, we propose the reliable data combining method for cooperative spectrum sensing, according to which the fusion center by u...

The spectacular growth in wireless services imposes scarcity in term of the available radio spectrum. A solution to overcome this scarcity is to adopt what so called cognitive radio based on dynamic spectrum access. With dynamic spectrum access, secondary (unlicensed) users can access spectrum owned by primary (licensed) users when it is temporally and/or geographically unused. This unused spec...