Abstract3GPP LTE has approved uplink intra-cell power control and defined overload indicator(OI)for uplink inter-cell power control to mitigate the inter-cell interference(ICI),respectively.In this paper,we propose a hierarchical power control(HPC)scheme where intra-cell and inter-cell power controls interact with each other.The inter-cell power control command is generated by radio resource management(RRM)entity according to the ICI-load model together with the current ICI and served load information.This ICI-load model is proposed as a guideline for coordination among cells to enable the system to approach its system specific interference over thermal noise(IoT)work area.Simulation results show that for HPC scheme,the system's IoT is well controlled to fit its pre-defined work area and the power efficiency is improved significantly.Our proposed scheme is also robust to different settings of its inter-cell power control period.
在正交频分复用(orthogonal frequency division multiplexing,OFDM)的多点协作(coordinated multi-point,CoMP)系统中,以子带为单位进行信道状态信息的反馈和预编码处理,可以有效降低反馈开销。但当参与协作的不同基站到达用户存在传输时延差时,会导致用户经历的等效信道多径时延扩大,增大子带内信道的起伏,进一步增大逐子带信道反馈的误差。该文分析了基站传输时延差对信道反馈误差的影响,提出了基于传输时延差长期统计值反馈的频域相位旋转法进行定时对齐,来改善传输时延差对逐子带处理OFDM-CoMP系统性能的影响。仿真结果表明:该方法只需增加较少的运算量及反馈信息即可获得明显的系统和速率增益,适用于实际OFDM-CoMP系统。
