On the impact of IQI on cooperative NOMA with direct links in the presence of imperfect CSI

Cooperative non-orthogonal multiple access (CNOMA) is considered as a promising technique to improve network coverage, reliability and transmission for future wireless communication networks. Meanwhile, transceivers can suffer from a number of hardware imperfections that will significantly reduce their performance, such as phase noise and in-phase/quadrature-phase imbalance (IQI). In this paper, we investigate the effect of in-phase and quadrature-phase imbalance (IQI) on CNOMA with direct links in the presence of imperfect channel state information (ICSI). The outage probability (OP) and throughput expressions are derived to evaluate the performance behaviors of the CNOMA with direct links under the IQI and ICSI imperfections. Theoretical analyzes are verified by Monte Carlo simulation. The effect of the IQI on the CNOMA with the direct links has been studied with different parameters (image rejection ratio (IRR), power allocation) and compared with conventional NOMA to clearly observe the degrading effects of imperfections on the systems. The simulation results demonstrate that the IQI and ICSI have a negative impact on the outage and throughput performance.     

Performance analysis of massive MIMO systems with low-resolution ADCs and IQI

In massive multiple-input multiple-output (MIMO) systems, the substantial increase in the number of antennas leads to a surge in hardware cost and power consumption. Meanwhile, the impact of IQ imbalance (IQI) on system performance also tends to be serious. In this paper, closed-form expressions for the achievable rates of maximum-ratio combining (MRC) receivers are derived for uplink massive MIMO systems with both low-resolution analog-to-digital converters (ADCs) and IQI. Based on the derived closed-form expression, the influence of system parameters on the achievable rate is analyzed. The simulation results verify the accuracy of the theoretical results. It is found that low-resolution ADC and IQI will degrade the achievable rate compared with employing high resolution ADCs, but this loss can be compensated for by increasing the number of base station (BS) antennas, so as to significantly increase the energy efficiency.     

B级IQI灵敏度的X-射线数字曝光曲线研究

基于非晶硅面阵探测器,以像质计(Image Quality Indicator,IQI)灵敏度达到成像质量最高级B级,研究了IQI灵敏度各制约参数并进行优化.基于优化理论和试验数据,以被检测物体的等效钢厚为自变量,将各制约参数的最优值集为一曲线,为数字射线成像（Digital Radiography,DR）检测提供有效的工艺参数.