Spectrum hand off in Cognitive Radio Network using Dynamic Threshold

The scarcity of spectrum is increasing day by day due to the spectrum scarcity faced by the wireless based service providers led to high congestion levels. The main reason that leads to inefficient utilization of the radio spectrum is the spectrum licensing system itself. If the allocated radio spectrum is not used by primary users, it cannot be utilized by secondary users. Due to this static and rigid allocation, wireless systems have to work only on a dedicated band of spectrum and cannot change the transmission band with the change in the environment. For example, if one channel of spectrum band is heavily used, the wireless system cannot change to work on another more lightly used band. To address these critical problems, the FCC recently approved the use of unlicensed devices in licensed bands. Consequently, dynamic spectrum access techniques are proposed to solve these current spectrum inefficiency problems. The key enabling technology for dynamic spectrum access techniques is CR networking which allows intelligent spectrum-aware devices to opportunistically use the licensed spectrum bands for transmissions. In Cognitive Radio Network(CRN) during the transmission period of a secondary connection, multiple interruptions from the primary users result in multiple spectrum hand offs and the need of determining a set of target channels for spectrum hand offs. A suitable hand off scheme has been proposed whose objective is to help cognitive user to find suitable channel to resume the unfinished transmission as quickly as possible. Dynamic Threshold approach is an important and one of the most authentic approaches in studying, modeling and analyzing the cognitive interaction process. The simulation results of the proposed scheme show that the model works well in increasing the throughput and packet delivery ratio in Cognitive Radio Networks.