Multidimensional Modulation Based On Orthogonal Transformation

Using orthogonal signal set for communication transmission has always been a common method in the field of communication.Nowaday,orthogonal frequency division multiplexing technology,a typical representative of this method,is still widely used as the physical layer modulation scheme of 4G and 5g communication.Another technology of this kind of method:orthogonal time-frequency-space system has been widely studied in academic circles because it is better than orthogonal frequency division multiplexing in multipath Doppler channel.This shows that the orthogonal signal transmission technology is still worthy of in-depth research.The research object of this paper is the application of multi-dimensional modulation technology and orthogonal transformation technology.All orthogonal transforms can be mapped into an orthogonal matrix after finite sampling.On the premise of ideal low-pass filtering,we are investigating the properties of the corresponding orthogonal matrix.We hope that the construction method of orthogonal transformation has a variety of controllable properties when constructing orthogonal transformation:sparsity,structure,low computational complexity,pseudo randomness,ergodicity,and so on.Therefore,we propose three construction methods of orthogonal transformation,which are controllable in the construction of orthogonal transformation based on the properties of the three orthogonal transformations.They are the multi-dimensional rotation transformation construction algorithm controlled by pseudo-random sequence,which focuses on the controllability of ergodicity and pseudo randomness respectively;Butterfly Iterative Construction Algorithm with low computational complexity;An orthogonal transformation construction algorithm based on Kronecker product,which focuses on sparsity and structural controllability.In different communication scenarios,we hope to use the multi-dimensional orthogonal transform provided by different orthogonal transform construction methods for signal modulation according to the different requirements of these scenarios for communication performance,so as to meet the communication requirements of these scenarios.We mainly study two scenarios:physical layer secure covert communication and high-speed mobile wireless communication.In the physical layer secure covert communication scenario,we will use the high pseudorandom orthogonal transform for signal modulation,and compare it with constellation scrambling technology and artificial noise technology to reflect the advantages of multidimensional modulation using orthogonal transform in physical layer secure covert communication.The simulation results show that the signal constellation is chaotic enough and the signal distribution tends to Gaussian distribution after modulation with high pseudo-random orthogonal transform.In the high-speed mobile wireless communication scenario,we use the sparse and structurally controllable Kronecker product construction method to construct the orthogonal transform for signal modulation,and analyze the modulated signal structure and signal diversity ability.The final simulation results show that this method can make the modulated signal transmit efficiently and reliably in the multipath Doppler channel.