为了避免认知超宽带系统对现有窄带授权通信系统造成的干扰,提高认知用户的频谱利用率,提出了一种正交多频带自适应脉冲设计方法.该方法首先将频带划分成若干个子带,根据信道特性生成自适应辐射掩蔽;然后利用有限项扁长椭球波函数来设计各子带脉冲;最后将各子带脉冲在时域上进行加权组合,并通过Gram-Schmidt正交变换生成一组可灵活切换频谱的正交自适应脉冲.仿真结果表明,在不影响授权用户的前提下,该脉冲可通过出让部分频带的方式继续占用空闲频带,降低了认知用户的中断率,提高了系统的频谱利用率.

In order to avoid the interference of cognitive ultra-wideband systems for the existing narrow-band autho-rized communications systems and improve the spectrum utilization efficiency of cognitive users,a design method of orthogonal multiband adaptive pulse is proposed.In this method,first,the band is divided into multiple subbands and the adaptive emission mask is generated according to channel characteristics.Then,the subband pulses are designed by using the finite prolate spheroidal wave function and are weightedly combined in the time domain.Finally,a group of orthogonal adaptive pulses with flexible handoff spectrum are produced via the Gram-Schmidt orthogonal transformation.Simulated results indicate that,without affecting the authorized users,the produced pulses reduce the termination probability of cognitive users and improve the spectrum utilization efficiency of the cognitive system through releasing the corresponding conflicted bands.