A Distributed Power Allocation for Cooperative Transmission in Cognitive Radio Systems
Guo Yan-yan①② Kang Gui-xia① Zhang Ning-bo① Zhang Ping①
①(Key Laboratory of Universal Wireless Communication, Beijing University of Posts and Telecommunications, Ministry of Education, Beijing 100876, China) ②(School of Physics and Electronics Engineering ShaXi University, Taiyuan 030006, China)
摘要 协作通信与直接通信相比能够显著地提高系统性能。协作通信中的一个关键问题是管理中继节点及有效地进行功率分配。尤其对于频谱共享的认知无线电(Cognitive Radio，CR)系统，协作方案的设计不仅要最大限度地提高认知网络协作的功率效率，而且需要最小化对主系统的干扰。该文针对认知无线电系统的协作通信问题，在多个中继节点与源节点协同通信的场景下，提出了一种基于放大转发(Amplify and Forward，AF)模式下的功率分配及联合优化算法，在保证主系统传输性能不受影响的前提下，提高认知系统的传输速率。仿真结果表明该文提出的自适应协作传输方案，和直接传输及等功率传输方案相比获得了进一步的性能增益，中断概率显著下降。
Abstract：The cooperative communication can get better performance of systems than the direct transmission. In particular, how to manage cooperative relays and allocate power among them especially for Cognitive Radio (CR) is one of the most important issue in wireless cooperative diversity systems. For CR systems, cooperative power allocation strategy need consider avoiding the interference with the primary (licensed) users. In this paper, a distributed transmit power allocation algorithm for multi-relays based on Amplify and Forward (AF) cooperative transmission is proposed for spectrum sharing CR systems. It optimizes the performance of the CR system, while the interference experienced by the licensed users is limited. The simulations validate the effectiveness of proposed algorithm by comparing it with the direct transmission and the scheme where equal weights are assigned to the relays.
2010, Vol. 32 
