Optimal Spectrum Management Strategy In Cognitive Radio

The cognitive radio by using the spectrum resources dynamically resolves the frequency problem of resource tension but low efficient greatly. However, due to the spectrum of cognitive users belong to the primary user, when the main user or the transmission channel degradation occurs, the cognitive users have to search for a new available spectrum. This feature makes the spectrum management strategy in the cognitive radio network face many challenges.This work studies the spectrum management in cognitive radio networks and the entire process of sending data, in which the process of spectrum sensing and detection in cognitive networks is explored by studying dynamic spectral characteristics of the network to find optimal algorithm and scheduling strategy to ensure communication between nodes. Research results obtained can be described as follows:1. A candidate set of free spectrum is built to help cognitive user to quickly perceive the available channels. According to time-based probability density estimation, the set of free spectrum is decided by sequence. When the cognitive user has perceived an idle channel, a threshold should be set to define channel as a good or bad one, which can reduce the transmission time and get the good throughput. By combining the channel quality into the candidate set, an initial frequency sequence is formed as frequency sensing priority.2. A frequency renew strategy is proposed. Facing the dynamical using environment, the system has to utilize some optimal way to efficient find another available frequency band. The old frequency will change to lower optimal position by one or some degree. The former is corresponds to the old frequency with free and bad quality, and the latter is under the unavailable old frequency one.The simulation analysis shows that the time delay is deed greatly reduced, and the system throughput can increase efficiently by comparing with the traditional method of inspection on the basis of perception. So, the optimal frequency management strategy can improve the network performance.