Research On3D MIMO Technology In LTE-advanced System

Based on the evolution of the LTE communication standard, we havestudied the3D MIMO technology in LTE R12. Base stations are availableto be equipped with planer antenna array due to the development of activeantenna system. And comparing to the traditional linear antenna array, theplanner antenna array could provide the degree of freedom that beam’sdirection could be adjusted in both horizontal and vertical domain. By fullyutilizing the spatial resources, we could improve the whole system’scapacity and coverage performance.First of all, we have studied the3D MIMO propagation property.Considering the dual-polarized antenna radiation and full spaceelectromagnetic wave propagation, we have built up a3D MIMO channelmodel. Based on the model, we have analyzed the capacity and spatialcorrelation property of3D MIMO and found that, although the systemcapacity could be improved by considering3D scattering, the efficiencylargely depends on the horizontal and vertical angle spread. Besides, wehave evaluated the effectiveness of Kronecker model under the assumptionof3D scattering. It is essential to study the channel properties before thedesign of system solutions.Secondly, we have studied the CQI selection and PMI selectionproblems from the link level perspective. By combining the maximumlikelihood detection and exponential effective SNR mapping technology,we proposed a bit-LLR wise EESM algorithm, which could abstract the physical layer with high accuracy and determine the CQI properly. Wehave also divided the3D MIMO precoding procedure into two steps, i.e.vertical beam steering and horizontal precoding. This could reduce thecomplexity of PMI selection and reuse the historical PMI design.Lastly, we have focused on the system deployment based on3DMIMO technology. Specifically, we have provided a solution to decoupingthe antenna downtilt selection and user selection problem. Our proposalsown the advantages of low complexity, low backhaul informationexchange, and no further standardization support is needed.Among the aforementioned three levels, the channel propagationproperties are of high importance as the start point of this dissertation; theCQI and PMI feedback schemes are the support technologies; and thesystem deployment based on vertical beam steering is the final applicationand destination. By studying and executing these three tightly-dependenttechonologies, we could fully take advantage of the3D MIMO spatialresources to enhance the communication system’s capacity and coverage.