Research On NOMA-MIMO Mechanism

The Multiple-Access Scheme is a key feature of a wireless system.Non-Orthogonal Multiple Access(NOMA)becomes an important candidate multiple access scheme of 5G system,while Orthogonal Multiple Access(OMA)is used by 4G/LTE system.The combination mechanisms of NOMA and MIMO have been researched in many literatures and most of them are from the perspective of theoretical research.So,the future research from perspective of engineering application is needed.Firstly,in this article,three kinds of typical traffic scenarios of 5G system are discussed and concluded that NOMA is more suitable to eMBB and mMTC.Secondly,a performance comparison between NOMA and OMA is made.At the beginning of this part,the down-link performance in AWGN channel is made and NOMA can achieve a higher multi-user channel capacity.Then an analysis of the down-link performance in the system using proportional fair algorithm is made which shows that NOMA can get a higher system throughput.At the end,it is proved that NOMA have lower packet loss rate in uplink of mMTC traffic through technical analysis and simulation.Thirdly,several foundational problems of NOMA are studied.The first problem is about Peak-to-Average Ratio due to power allocation of NOMA are studied and a new method is provided to solve it.The second problem is that the current scheduling method is not suitable for time-sensitive traffic.An optimized proportional fairness algorithm is developed to solve this problem.At last,based on the characteristics of NOMA,a new method for NOMA-HARQ retransmission is proposed.Fourthly,the combination mechanism of NOMA and single-cell MIMO(NOMA-MIMO)is presented,along with a novel method of UE paring and simulation results.At first,the system mode of the combination mechanism of NOMA and single-cell MIMO is provided.And then a novel method of UE paring with low complexity is developed based on the analysis of the typical scenarios of NOMA-MIMO.The simulation results show that NOMA-MIMO can get better performance of throughput comparing to OMA-MIMO and the novel method of UE pairing with low complexity can achieve similar performance of throughput as ideal-pairing with highcomplexity.Finally,the combination mechanism of NOMA and CoMP(NOMA-CoMP)is studied and further divided into two scenarios.One scenario is that the component AP of CoMP is with single antenna and another scenario is that the component AP of CoMP is with multiple antennas.First of all,the issue of the inter-AP phase difference of NOMA-CoMP is analyzed.For the scenario of AP with single antenna,a new scheme is provided to calibrate the phase difference of inter-AP and simulation results show that this new scheme can work well.For the scenario of AP with multiple antennas,two issues are discussed.One issue is about the phase calibration of DL-UL duplex of inter-AP.A novel scheme based on the combination of Sounding RS measurement at eNB and PMI fed back by UE is provided to solve the issue.The simulation results show that the calibration accuracy of phase difference using this novel scheme can be reached to ? 8.Another is about the channel estimation issue due to the channel discontinuity led by subband-precoding.A new scheme by aligning the phases of the first element of each row of V matrix of SVD of different frequency subband is provided.The simulation results show that the new scheme can get better performance of channel estimation in subband-precoding scenario.