Acta Metallurgica Sinica(English letters) ›› 2010, Vol. 17 ›› Issue (3): 24-30.doi: 10.1016/S1005-8885(09)60475-1

• Wireless • 上一篇    下一篇

Multicast resource allocation with min-rate requirements in OFDM systems

许文俊1,贺志强2,林家儒3,牛凯2,吴伟陵2   

  1. 1. 北京邮电大学,信息与通信工程学院,信息理论与技术教研中心
    2.
    3. 北京邮电大学
  • 收稿日期:2009-10-10 修回日期:2010-01-21 出版日期:2010-06-30 发布日期:2010-06-29
  • 通讯作者: 许文俊 E-mail:snowofsouth@gmail.com;wjxu@bupt.edu.cn
  • 基金资助:

    国家级.国家自然科学基金;国家级.国家自然科学基金重大研究计划项目

Multicast resource allocation with min-rate requirements in OFDM systems

  • Received:2009-10-10 Revised:2010-01-21 Online:2010-06-30 Published:2010-06-29

摘要:

This article addresses the multicast resource allocation problem with min-rate requirement constraints in orthogonal frequency division multiplexing (OFDM) systems. Due to the prohibitively high complexity for nonlinear and combinatorial optimization, the original problem is relaxed and reformulated to form a standard optimization problem. By theoretical derivation according to the Karush-Kuhn-Tucker (KKT) conditions, two propositions are presented as the necessary criteria for optimality. Furthermore, a two-step resource allocation scheme, including subcarrier assignment and power allocation, is proposed on a basis of the propositions for practical implementation. With the min-rate based multicast group order, subcarriers are assigned in a greedy fashion to maximize the capacity. When subcarrier assignment is determined, the proposed power allocation can achieve the optimal performance for the min-rate constrained capacity maximization with an acceptable complexity. Simulation results indicate that the proposed scheme approximates to optimal resource allocation obtained by exhaustive search with a negligible capacity gap, and considerably outperforms equal power distribution. Meanwhile, multicast is remarkably beneficial to resource utilization in OFDM systems.

关键词:

OFDM, multicast, resource allocation, min-rate requirements

Abstract:

This article addresses the multicast resource allocation problem with min-rate requirement constraints in orthogonal frequency division multiplexing (OFDM) systems. Due to the prohibitively high complexity for nonlinear and combinatorial optimization, the original problem is relaxed and reformulated to form a standard optimization problem. By theoretical derivation according to the Karush-Kuhn-Tucker (KKT) conditions, two propositions are presented as the necessary criteria for optimality. Furthermore, a two-step resource allocation scheme, including subcarrier assignment and power allocation, is proposed on a basis of the propositions for practical implementation. With the min-rate based multicast group order, subcarriers are assigned in a greedy fashion to maximize the capacity. When subcarrier assignment is determined, the proposed power allocation can achieve the optimal performance for the min-rate constrained capacity maximization with an acceptable complexity. Simulation results indicate that the proposed scheme approximates to optimal resource allocation obtained by exhaustive search with a negligible capacity gap, and considerably outperforms equal power distribution. Meanwhile, multicast is remarkably beneficial to resource utilization in OFDM systems.

Key words:

OFDM, multicast, resource allocation, min-rate requirements