Non spectrum handover link maintenance performance in cognitive radio

Cognitive radio (CR) is a promising wireless communications technology. When using NC (non contiguous)-OFDM to transmit data, CU (cognitive user) promptly evacuates the channel reused for communication once PU's (Primary User's) reappearance is detected, and needs to acquire new channel. One way is to increase modulation rate on remainder uninterfered channels, while the other is to acquire new channels. Acquiring new subcarriers takes a great portion of the link maintenance time. This paper proposes using increased modulation mode to keep the same transmission data rate so that CU can save the time of acquiring new channel. Numerical result shows that the goodput of increased modulation rate method is 14 Mb/s advantageous over that of acquiring new channel.