Abstract: The authors propose a resource allocation algorithm for orthogonal frequency division multiplexing (OFDM) system to provide QoS guarantee for multicast and unicast service concurrently. The optimization objective is to maximize the sum rate of the unicast users under the constraints of power and the minimal rate requirements of multicast service, which can be solved by traditional two-step approach. To decrease the complexity, a greedy-based approach is proposed. According to theoretical analysis and simulation results, the performance of the proposed algorithm is close to the two-step approach meanwhile the complexity is effectively decreased. In summary, the proposed algorithm can balance the performance and complexity well and is suitable to be applied to the practical scenario.

Key words: orthogonal frequency division multiplexing (OFDM), multicast, subcarrier allocation, power allocation

摘要： 研究了OFDM 系统中同时支持组播与单播业务时的资源分配问题。针对组播与单播业务的不同 QoS 要求,将资源分配问题建模为在保证组播业务所要求的最小速率的条件下, 最大化单播业务和速率的分配问题。该问题可利用传统的两步法求解。为了进一步降低复杂度, 提出了一种基于贪婪方法的分配算法, 其基本思想是首先通过子载波分配满足组播业务的最小速率要求, 进而在所有子载波之间调整功率以提高单播业务的和速率。理论分析与仿真结果表明, 所提出的算法能够有效地降低复杂度, 且在满足组播最小速率要求的条件下, 单播业务所能获得的和速率接近两步法, 较好地实现了算法的性能与复杂度之间的平衡。

关键词: 正交频分复用, 组播, 子载波分配, 功率分配