| With the development trend of intelligent communication terminals and diversified communication services,the new generation of mobile communication technology represented by MIMO system has become a research hotspot.Array antennas are used at both ends of MIMO system.On the basis of controlling correlation and improving spatial separability,the concept of diversity technology improves the multiplexing of space and time,so as to meet the high requirements of users on the capacity and rate of communication system.Compared with the traditional single input single output wireless communication system,which can only send or receive one data stream at a time,MIMO system has a good development prospect in limited band wireless communication.Therefore,the research on the channel model and characteristics of MIMO system has important application value.The traditional statistical model and empirical formula are formula fitting and abstract modeling of channel characteristics from the perspective of information theory.When aiming at the actual propagation scene,it does not form a set of effective research methods.Therefore,this paper uses ray tracing algorithm to model and analyze the deterministic channel characteristics of MIMO system in specific propagation environment,and studies the correctness of its system model and the factors affecting its performance combined with experimental measurements.The specific research contents and main research results are as follows:1.Research on channel characteristics of microcell MIMO system.Starting from the MIMO deterministic channel model based on ray tracing algorithm,this paper introduces the flow of modeling and simulation algorithm in detail.The MIMO channel in urban microcell,a popular application scenario,is simulated in detail.The influence of the putting-up environment of the transceiver on the overall channel power,delay and other parameters is analyzed.Combined with the empirical model,the simulation of MIMO system channel capacity is compared and verified.Based on the channel state information feedback to the transmitter,the transmission mode is optimized through the power allocation algorithm to improve the system channel capacity.2.Research on MIMO system channel in O2 I scenario.In this paper,aiming at the outdoor to indoor(O2I)scene in urban environment,combined with the geometric characteristics and electromagnetic characteristics of propagation scene,the classification and fine modeling are carried out to make the prediction results more accurate.At the same time,aiming at the complexity of multipath in O2 I scenario,the traditional channel clustering algorithm is improved to facilitate the study of MIMO system channel characteristics.Combined with the analysis of measured data,the applicability and accuracy of the deterministic model are verified.The simulation analysis of the capacity of large-scale MIMO array antenna system in O2 I scenario is completed.3.Research on millimeter wave MIMO channel in rainfall scenario.Based on the raindrop particle attenuation theory,this paper completes the calculation and Simulation of characteristic rain attenuation,and verifies the influence of raindrop spectrum on rain attenuation rate through simulation.The field experiments were carried out,and the experimental data were compared to verify the error of the traditional model error and the "amplification-effect" of multipath-effect on rainfall attenuation.Combined with the literature,the rain attenuation model was modified based on the raindrop spectrum and multipath effect in Xi’an,and the MIMO system capacity and bit error rate under the rainfall scene were simulated.To sum up,this paper constructs a deterministic channel model based on the actual scenarios,and studies the channel propagation characteristics and system performance factors of MIMO system in typical scenarios in daily life.The research results of this paper provide some reference value for MIMO system application and base station erection in specific scenarios. |
PDF Full Text Request