【摘要】 非连续正交频分复用(Non-continuous orthogonal frequency division multiplexing,NC-OFDM)技术是认知无线电(Cognitive radio,CR)的一项应用。在NC-OFDM通信系统中,认知用户感知无线环境中授权频段的频谱空洞(Spectrum hole)并加以利用,以减少频谱的浪费。为保证授权用户的通信质量,认知用户需要在授权用户接入通信时立即退出,这使NC-OFDM通信系统对实时性要求较高,适用于OFDM通信系统的传统资源分配算法无法满足实时性要求。基于NC-OFDM系统的频谱特点,提出两种快速资源分配算法。所提出的算法首先依据误比特率与增益噪声比计算功率门限,采用一次判断选出认知用户使用的子信道,降低解空间维数;接着直接计算注水常量,进行初始资源分配;最后基于二分思想对已排序的子信道(方法 1)或未排序的子信道(方法 2)进行剩余资源的分配。理论分析与仿真结果表明,提出的快速资源分配算法与最优算法的资源分配结果相同(方法 1)或相近(方法 2),复杂度更低,资源分配的速度更快。更多还原

【Abstract】 Non-continuous orthogonal frequency division multiplexing(NC-OFDM) technology is an application of cognitive radio(CR). In NC-OFDM communication systems,cognitive users sense the spectrum holes in authorized frequency to reduce the waste of spectrum resources. In order to ensure the communication quality of authorized users,cognitive users need to exit immediately when authorized users access,which makes the real-time requirements of NC-OFDM systems higher than those of OFDM systems. Traditional resource allocation algorithms designed for OFDM systems cannot meet real-time requirements. Considering the spectrum features of NC-OFDM systems,two fast resource allocation algorithms are proposed:Firstly,the power threshold is calculated based on the bit error rate and gain-tonoise ratio,and a single judgment is used to select the sub-channels used by the cognitive users,which reduces the dimensionality of the solution space;Secondly,the water-level is calculated directly and the power and bit allocation are initialized. Finally,based on dichotomy,the remaining resource of sorted channels(method 1) or unsorted channels(method 2) is allocated. The theoretical analyses and simulations show that the proposed algorithms have the same(method 1)resource allocation results or the similar resource allocation results(method 2)as the optimal algorithm. The calculation complexity of the proposed methods is lower,which significantly speeds up resource allocation.更多还原