Optimal Frequency Hopping Code Design For OFDM Systems And LTE FDD Network Coverage Analysis

In recent years, the data rate of the mobile communications network to enhance more and more obvious, the operators in the planning and construction of 4G network has accumulated a wealth of experience. But for the entire network coverage, especially low frequency coverage is still at the preliminary exploration stage. Based on the project of LTE wireless network planning from China Telecom,this thesis makes analysis and researches on the influence on the orthogonal properties among sub-carriers in OFDM system due to doppler frequency shift and the feasibility of LTE FDD 800 MHz band network construction.Firstly, the background and the status of subject is described. To solve the problem that the influence on the orthogonal properties among sub-carriers in OFDM system due to the time delay and doppler frequency shift. By coding a computer program to calculate the correlation function sequence, explores the hopping pattern which has both an ideal self-correlation and co-correlation of frequency hopping pattern. And introduce the design method of optimal frequency hopping codes.Secondly, the feasibility of LTE FDD 800 MHz band network construction is analyzed. By using the link budget approach, it analyzes the link budget table of 800 MHz band and 1.8 GHz band LTE FDD in dense urban, the typical urban, suburban and rural areas and comes to a conclusion. It shows that the coverage of 800 MHz upgrades 80% compared to 1.8GHz without taking into account the coverage of overlapping base station area and the coverage rural and suburban increase significantly compared to the main city by 800 MHz. Then it simulates the coverage of industrial areas and residential areas in a city by using the Aircom simulation software. It simulates to build base station with 800 MHz and 1.8GHz respectively in original sites of CDMA 800 MHz. Then it shows the coverage of 800 MHz upgrades 20% compared to 1.8GHz in industrial areas and upgrades 17% in residential areas. The result obtained in this research is that the 800 MHz frequency band compared to 1.8GHz has a higher coverage when constructing the base station at the existing network sites especially the current site address haslargergaps, such as suburban and rural.Thirdly, it offers some proposals on the whole network construction by analyzing the schemes of frequency options. According to the current CDMA 800 MHz carrier configuration, it analyzes that the two schemes that using the 800 MHz LTE FDD network in existing spectrum. These schemes are named Lower edge and Sandwich. According to the characteristics of the two schemes, it suggests that choosing the Lower edge if the operators consider adding bands lower than 800 MHz and else choosing the Sandwich that could reduce the impact on the existing network.In summary, by coding a computer program of calculation sequence correlation function, it simplifies the optimal design method of frequency hopping codes. The feasibility of LTE FDD 800 MHz band network construction based on a project of China Telecom and offered some construction proposals is analyzed. It provides a reference for the design and optimization of the 4G network in the future.