【摘要】 将自适应技术应用于多用户正交频分复用(OFDM)系统,能够提高频谱利用率,降低系统发射功率,从而使系统的整体性能达到最优.文中给出了多径频率选择性衰落信道下多用户OFDM系统中自适应比特和功率分配的数学模型,提出了一种次优快速自适应分配算法,根据信道特性的瞬时估计值,自适应地为各用户分配子信道和比特,在给定误码率的条件下使总的发送功率最小.仿真结果表明,该算法计算简单,优化效率高,可以达到接近理论上的最优水平.更多还原

【Abstract】 The application of adaptive technology to the multiuser OFDM (Orthogonal Frequency Division Multiplexing) system can increase the spectrum usage, reduce the transmission power of the system and optimize the system performance. In this paper, a mathematical model for the adaptive bit and power allocation in the multiuser OFDM system in frequency selective fading channels is proposed, and a rapid sub-optimal adaptive allocation algorithm is presented. According to the estimation of instantaneous channel characteristics, the adaptive allocation algorithm can assign the subchannels and bits for each user in the system to minimize the total transmission power with a given bit error rate. Simulated results show that the proposed algorithm is simple in calculation, high in efficiency and optimal in theory as the optimal scheme.更多还原