| This graduation thesis focus on the FD-MIMO (Full-dimension Multiple-Input and Multiple-Output) and NOMA (Non-Orthogonal Multiple Access) stud-ies. The studies are based on the evolution of LTE-A (Long Term Evolution-Advanced) which is standardized by3GPP (The3rd Generation Partner Project). Different from the conventional MIMO system, FD-MIMO can leverage the significantly increased freedom offered by the advanced antenna arrays with large number of antenna elements which can be adjusted individually. Thus the transmitter can adjust the beam direction to concentrate the energy to the user of interests while minimizing the interference leakage to co-scheduled users in the same cell or users in the neighbouring cells. However, the compatibility with exciting LTE-A standard is still an open issue. The3D-MIMO channel mod-elling, FD-MIMO precoding schemes and reduction of reference signal over-head are the key problems of this issue. In addition to that, we study the NOMA system. NOMA is one of the promising multiple access scheme in the future wireless communication systems. LTE-A adopts the OMA (Orthogonal Mul-tiple Access) which is based on the OFDMA (Orthogonal Frequency-Division Multiple Access) as the multiple access scheme. Different from OMA sys-tem, NOMA system support multiple users transmit in the same frequency and time resource block. User separation mainly relies on superposition code with smart power allocation at the transmitter side and advanced signal processing at the receiver side. But the standardization of NOMA system is not initialized. Some key problems, such as the power allocation methods, design of NOMA signalling and scheduling algorithms are still need to be further studied.In order to solve the problems mentioned above, this graduation thesis are separated in three parts:First, we study the3D MIMO channel modelling, including the procedure of3D-MIMO channel modelling and the implemen-tation of3D-MIMO channel in LTE-A system level simulator. Second, the performance of FD-MIMO system is investigated; Third the performance and standardization of NOMA system are discussed in this thesis.For the study of3D MIMO channel modelling, this thesis introduce the channel modelling procedure which is proposed by the3GPP. Simulation sce-narios, three dimensional user distribution and channel modelling are studies. And we implemented the modelling mentioned above in the LTE-A system level simulator. Based on the study of channel modelling and simulation, we have below findings:First, the three dimensional user distribution is more realistic; Second, in3D-MIMO channel modelling, the distribution of elevation angles are much more narrower than horizontal angles. Thus the conventional code-book which was designed to suit the2D-MIMO may be not applicable to3D-MIMO.For the study of FD-MIMO system, we study the precoding schemes of FD-MIMO system based on the3D-MIMO channel. To begin with, we pro-pose one novel FD-MIMO precoding scheme based on the subspace tracking. Then, we simulated the precoding schemes in LTE-A system level simulator. According to the simulation results, the proposed method can increase the sys-tem performance and reduce the reference signal overhead to the maximum.For the study of NOMA system. First, we verified the NOMA system can improve the system performance compare with OMA system. Then, we discussed the compatibility of existing LTE-A system including the system scheduling methods, power allocation methods and signalling overhead. |
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