【摘要】 研究了在总功率的约束下,组播OFDM系统中最大化组播速率的功率分配问题.首先引入贪婪算法求解该问题以降低复杂度,但贪婪算法只执行预设的固定次数分配后即停止,其截止条件与功率分配过程中的状态无关,无法有效地提高系统性能;进而提出了两种基于子载波成对调整的功率分配算法,在初始功率分配的基础上选择子载波对交换功率,将功率重新分配给能够使组播速率提高得最多的子载波,并只在无法进一步提高组播速率时才停止调整.研究和仿真结果表明,所提出的两种调整算法能够有效地提高组播速率,性能接近根据凸函数优化方法求得的最优解,且显著降低了算法的复杂度.更多还原

【Abstract】 The power allocation problem to maximize the multicast rate in one multicast group under the total power constrain is investigated in multicast Orthogonal Frequency Division Multiplexing(OFDM) system.The greedy algorithm is applied to reduce the complexity.To improve the multicast rate,two power allocation algorithms based on subcarrier pairwise exchange are proposed.The proposed algorithms both have two steps:initial power allocation and adjustment.During the adjustment period,power is exchanged between subcarriers and the algorithms are terminated only when the multicast rate cannot be increased any more.Simulation results show that the proposed algorithms can achieve near optimal result with low complexity.更多还原