基于OFDM的双层Femtocell网络中子信道、速率和功率的最优分配

摘要

Femtocell(毫微微小区)基站通过以极低的功率对室内进行"点"覆盖,降低了宏小区基站的传输功率要求和业务负荷量,使得整个系统的功率效率得以提高.研究了双层Femtocell网络中,考虑到宏小区和毫微微小区之间、不同毫微微小区之间所存在的同频干扰,在满足宏小区用户传输性能不受影响的前提下,对毫微微小区用户的子信道、速率和功率进行联合优化分配的方法,以使其加权速率和最大.针对问题的非凸性,提出了基于拉格朗日对偶方法的最优子信道、速率和功率分配算法,并从经济学的角度予以解释.最后,通过仿真验证了此算法可以有效地求解此问题,并且证明了该系统相对于宏小区和毫微微小区使用不同频率集的系统可以很大程度地提高系统性能,与此同时也提高了频谱利用率.%The problem of subchannel, rate and power allocation in OFDM-based two-tier Femtocell networks, which comprises a conventional macrocell and multiple Femtocells, is addressed. Our objective was maximizing the multiple Femtocell users' weighted rate sum by jointly adjusting their subchannel, rate and power allocation under the constraints of cross-tier interference (CTI) between macrocell and multiple Femtocells and the cochannel interference (CCI) between multiple Femtocells. We formulated this optimization problem and solved it using the Lagrangian dual method and interpreted it from the angle of economics. Simulation results show that our system has better performance than the usually employed system, in which the Femtocells can only use the subchannels unoccupied by macrocell. Meanwhile, the utilization of spectrum can be improved significantly.