Acta Metallurgica Sinica(English letters) ›› 2010, Vol. 17 ›› Issue (6): 41-46.doi: 10.1016/S1005-8885(09)60523-9

• Wireless • 上一篇    下一篇

Optimal power allocation for multi-user OFDM and distributed antenna cognitive radio with RoF

葛文栋1,纪红1,司鹏搏2   

  1. School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China
  • 收稿日期:2010-01-29 修回日期:2010-07-15 出版日期:2010-12-30 发布日期:2010-12-06
  • 通讯作者: 葛文栋 E-mail:gwd77777@gmail.com
  • 基金资助:

    国家级.国家自然科学基金;国家级.国家“863计划”项目

Optimal power allocation for multi-user OFDM and distributed antenna cognitive radio with RoF

  1. School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China
  • Received:2010-01-29 Revised:2010-07-15 Online:2010-12-30 Published:2010-12-06

摘要:

In cognitive radio (CR), power allocation plays an important role in protecting primary user from disturbance of secondary user. Some existing studies about power allocation in CR utilize ‘interference temperature’ to achieve this protection, which might not be suitable for the OFDM-based CR. Thus in this paper, power allocation problem in multi-user orthogonal frequency division multiplexing (OFDM) and distributed antenna cognitive radio with radio over fiber (RoF) is firstly modeled as an optimization problem, where the limitation on secondary user is not ‘interference temperature’, but that total throughput of primary user in all the resource units (RUs) must be beyond the given threshold. Moreover, based on the theorem about maximizing the total throughput of secondary user, equal power allocation algorithm is introduced. Furthermore, as the optimization problem for power allocation is not convex, it is transformed to be a convex one with geometric programming, where the solution can be obtained using duality and Karush-Kuhn-Tucker (KKT) conditions to form the optimal power allocation algorithm. Finally, extensive simulation results illustrate the significant performance improvement of the optimal algorithm compared to the existing algorithm and equal power allocation algorithm.

关键词:

cognitive radio, power allocation, OFDM, distributed antenna, convex optimization, radio over fiber (RoF)

Abstract:

In cognitive radio (CR), power allocation plays an important role in protecting primary user from disturbance of secondary user. Some existing studies about power allocation in CR utilize ‘interference temperature’ to achieve this protection, which might not be suitable for the OFDM-based CR. Thus in this paper, power allocation problem in multi-user orthogonal frequency division multiplexing (OFDM) and distributed antenna cognitive radio with radio over fiber (RoF) is firstly modeled as an optimization problem, where the limitation on secondary user is not ‘interference temperature’, but that total throughput of primary user in all the resource units (RUs) must be beyond the given threshold. Moreover, based on the theorem about maximizing the total throughput of secondary user, equal power allocation algorithm is introduced. Furthermore, as the optimization problem for power allocation is not convex, it is transformed to be a convex one with geometric programming, where the solution can be obtained using duality and Karush-Kuhn-Tucker (KKT) conditions to form the optimal power allocation algorithm. Finally, extensive simulation results illustrate the significant performance improvement of the optimal algorithm compared to the existing algorithm and equal power allocation algorithm.

Key words:

cognitive radio, power allocation, OFDM, distributed antenna, convex optimization, radio over fiber (RoF)