Increasing the Spectrum Efficiency of a Cognitive Radio Network
Hiral Mehta, Sonali Paralkar, Krupesh Ved, Dayanand D. Ambawade · Cyber-Enabled Distributed Computing and Knowledge Discovery · 2013
In this project, we propose a model of cognitive cellular network where secondary users are permitted to transmit in the licensed bands if a spectral hole is detected. We use energy detection at each secondary node and the secondary nodes further form clusters based on k-means algorithm. Each cluster has a fusion node or a cluster head which makes the final decision about the spectral hole based on cooperation among its own cluster users individual decisions. Since primary users use OFDM to transmit the data, it is extremely essential to estimate the channel between the primary user and secondary user to determine which sub carriers are underutilized by the primary user. These null sub carriers are further utilized by the secondary user to transmit its own data by a technique known as Non Contiguous OFDM which ensures minimum interference to the licensed user. The assignment of channels to a single cluster is done based on the interference posed by every user on that channel and all the secondary users can further use this channel by employing iterative water filling algorithm and NC-OFDM.