Research On Key Technologies Of Orthogonal Pattern Division Multiple Access Communication System Based On Optimal Frequency Hopping Patterns

Cellular mobile system is interference limited,that is,the interference in the system is far greater than the background noise,so the increase of the number of users in the system is mainly limited by the degree of interference.Therefore,any multiple access technology that can reduce interference can directly improve the capacity and performance of the system.In the past decades of the development of mobile communication,the proposal of frequency division multiple access,time division multiple access and code division multiple access technology has greatly improved the system performance.However,the traditional multiple access technology is one-dimensional and can not effectively overcome the interference caused by multipath propagation and Doppler frequency shift.The interference caused by multipath delay is usually solved by equalization,but there is no effective solution for the interference caused by Doppler frequency shift.In this paper,a two-dimensional orthogonal multiple access which can effectively overcome the interference caused by multipath propagation and Doppler frequency shift is proposed,that is,orthogonal graph division multiple access.The principle of orthogonal graph division multiple access technology is expounded,and it is applied to cellular mobile communication system to realize orthogonal graph division multiple access communication.In the mobile communication system,the orthogonal graph division multiple access based on the optimal frequency hopping graph can eliminate or reduce the interference caused by multipath propagation and Doppler frequency shift,reduce the bit error rate,and improve the system capacity and communication quality.The technologies such as large-scale MIMO and intelligent reflector proposed for the future cellular mobile communication system are also suitable for this orthogonal graph division multiple access communication system based on the optimal frequency hopping graph.The key technology of orthogonal graph division multiple access is to design a sufficient number of optimal frequency hopping graphs with ideal autocorrelation and cross-correlation characteristics.Obtaining the optimal frequency hopping graph is the focus and difficulty of the research.The optimal frequency hopping graph is based on the Costas sequence with ideal autocorrelation constructed by algebra.The two-dimensional cyclic shift of the Welch Costas sequence and Golomb Costas sequence constructed by algebra can construct a sufficient number of optimal frequency hopping graphs,This paper introduces in detail the method of constructing the optimal frequency hopping diagram by two-dimensional cyclic shift method.By calculating and comparing the autocorrelation and cross-correlation performance of Costas sequence and the optimal frequency hopping diagram,the model of cellular mobile communication system based on the optimal frequency hopping diagram is given.According to the architecture of cellular mobile communication system,the frequency hopping diagram of users of cellular mobile communication system is designed,and this new two-dimensional orthogonal graph division multiple access technology is adopted,The interference caused by multipath propagation and Doppler frequency shift can be effectively overcome without equalization and channel estimation.Therefore,the complexity of the receiver can be greatly reduced and the system performance can be improved.Orthogonal graph division multiple access,as a new two-dimensional orthogonal multiple access technology different from FDMA,TDMA and CDMA,will have a significant and far-reaching impact on the future mobile communication.