Research On Propagation Model And Model Calibration Algorithm Based On LTE System

Modern communication technology develops as fast as science technology does. China’s wireless network evolution change from3G to4G, LTE time is coming. Propagation model calibration is the basis of next-generation cellular wireless network (NGWN) pre-planning, Propagation model’s accuracy directly affects the rationality of wireless network planning and optimization, and the quality of communication ultimately. Therefore, the research on propagation models and the calibration algorithm is extremely important.Model calibration depends on the appropriate propagation model which is intimately related to the communication environment, and it has lots of randomness. Propagation model are used to predict the path loss on the radio wave path. Different model has different propagation path loss formula, although classical propagation models have considerable general applicability, but they need a detailed analysis for the specific environment. This paper describes the principles of classical propagation model and summarizes the comparison of its propagation characteristics, simulates and analysis the Okumura-Hata model, COST-231Hata model and SPM model. The results show that for the dense urban propagation environment of LTE system, SPM model is the most suitable system propagation model.Due to rapid development of urbanization in China, the geomorphic environment in the dense urban area is becoming more and more complex, which has decreased the accuracy of propagation model calibration and increased the difficulty of creating propagation model. In order to improve the accuracy of dense urban area model calibration and get the propagation model matching the local propagation model, fitting correction method, a dollar correction method and the improved propagation model calibration method are used to calibrate propagation model respectively with measured data. Improved propagation model correction algorithm is based on WLS algorithm, which eliminates the heteroscedasticity of sampling point and improves the effectiveness of the sampling data. Otherwise, it considers clutter (i) value obtained by calculation, so as to propagate the model to reflect the changes in the topography of the local propagation environment and improve the matching degree obtained. According to the improved correction algorithm, model calibration software is carried out on matlab/GUI development platform in this paper, the software enables import CW data, output correction equation, and error analysis. With the corrected propagation model path loss formula, link budget is conducted in this paper. The link budget tables of up and down rows can be contained based on the parameters messaging client, and it can lay the foundation for the c latter overage analysis.In this paper, model calibration is based on the measured CW data of the LTE system. The results showed that predicted data’s error decreased by5dB when proceeding large-scale propagation model calibration in dense urban area with complex geomorphic environment. This indicated that the improved propagation model calibration method is more accurate than the others and propagation model became more accurate and reflected local propagation environment better after calibration.