Adaptive signature waveforms design for cognitive radio system

Recently, with the fast development of wireless communications, the radio spectrum has become a precious natural resource. Cognitive radio (CR) has been proposed as an important means to promote efficient use of the spectrum by exploiting the existence of spectrum holes. In this paper, we utilize wavelet packets to achieve spectrum management and signature waveform design for CR users. With legacy users using fixed signature waveforms of frequency division multiple access and wavelet packets, respectively, our simulations show that the proposed two-phase spectrum management and signature waveform design algorithms can effectively reduce the interference between the CR and legacy users and improve the performance of both.