The Simulation Research Of OFDM-OVCDMA System Under Cofrequency Networking

High spectrum efficiency transmission and networking are necessary in future wireless communication due to the explosive growth of mobile services and the limited frequency resources.Based on information theory, coding theory and wireless channel characteristic, Prof. Li Daoben proposed an Overlapped Multiplexing theory and a series technology of Overlapped Multiplexing and Accessing. Overlapped Code Division Multiplexing (OVCDM) and Overlapped Code Division Multiple Access (OVCDMA) are the key technologies especially.Combined with the existing OFDM technology,it can greatly improve the capacity and spectrum efficiency of wireless communication systems.In this paper, several key technologies of OFDM-OVCDMA system is studied. First,the paper studies the four-color networking mode base on time-frequency coding which combined OVCDMA with OFDM.This mode using the othogonal time-frequency code sequence of OFDM subcarriers to distinguish the traffic channel of different cells, it can not only vanish the inter-cell interference,but also against the frequency selective fading and time selective fading of wireless communication channel effectively. Then verifies the performances of Space Zero Correlation Windows pilot under this networking mode and the pilot of Long Term Evolution is compared.It proves that the performance of continuous pilot is much better than LTE pilot under the same speed. Finally it analyzes a superposition coding and decoding method based on Successive Interference Cancellation(SIC).