This paper presents three compact ultra-wideband(UWB)antennas fed by coplanar waveguide(CPW).The proposed antennas consist of a planar circular patch monopole UWB antenna and multiple etched slots on the feed line.Simulation by Ansoft high frequency structure simulator(HFSS)10.0 shows that the in-band impedances are quite stable and satisfactory.Rejected narrow frequency bands are further obtained within the wideband width by inserting U-shaped slots into the fed line of the antennas.The antennas have a dimension of 50mm by 40mm by 1.5mm.The simulation and measurement results show that the proposed antennas have stable directional radiation patterns,very low profile and low fabrication cost,which are suitable for the UWB system.
该文针对闭环多用户MIMO-OFDM系统提出一种基于线性预测的低速率CSI(Channel State Information)反馈方法。根据相关带宽将OFDM子载波划分成多个子带,移动台对每个子带的CSI作线性预测,并对预测误差进行量化编码后反馈给基站;基站使用相同的线性预测滤波器将反馈来的预测误差恢复成CSI,然后在每个子带上通过迫零-波束赋形实现多用户空间复用。同时,该文还在采用注水定理分配发射功率的条件下,从理论上分析了下行链路信道容量。数值仿真结果显示,每个反馈数据的实部或虚部仅用1bit量化时,本方法仍能够以较高的精度恢复CSI。与目前3GPP LTE标准所采用的基于码书的反馈方案相比,该方法能够在反馈开销相同情况下,有效地抑制同信道干扰,大幅提高系统容量。
