Research On High-Dimension Modulation Based On Sphere Packing

Recently, with the rapid development of communication technology, the information level of our city increases continuously. In that case, many data business costing large capacity, such as the online game(the cloud game), high-definition video, the cloud storage and so on. At the same time, the number of Internet users increases significantly, because of the rapid development of the Internet technology in recent years, which causes higher requirements for the transmission performance of communication network. In that case, how to guarantee the transmission capacity and improve the reliability of the communication system simultaneously has become an important issue to be solved. In order to solve the problem above, researchers began to focus on the design of the modulation format at the transmitter. Previous studies in theory have illustrated that the transmission capacity could be improved when using the high-order modulation format. However, the power efficiency will be reduced on the contrary, which reduces the transmission distance. In order to ensure the transmission capacity while still having far transmission distance, the high-dimension modulation format comes into being. The basic idea is to use the modulation of the signal as the degree of freedom, such as the polarization state x, y, the in-phase and quadrature component, different time slot, carrier, and the mode and so on. Due to the high-dimension modulation technique is composed of multiple degrees of freedom to load the signal so the transmission capacity and distance could be larger. However, as a new modulation format, the high-dimension modulation still has many problems to be solved, including constellation points in high-dimension space, mapping problem in high-dimension symbols and the problem of high-dimension demodulation. Good spatial constellation distribution can increase the minimum Euclidean distance between constellation points, which can increase the progressive power efficiency of the modulation format. Therefore, how to choose the constellation points is the importance issue to be solved for the high-dimension modulation firstly. The research of the high-dimension mapping theory is still in its infancy. Efficient methods of the high-dimension mapping haven’t to be put forward yet. In that case, when we want to achieve a great development of the high-dimension modulation technique, the high-dimensional mapping technology is also the important issues needed to be solved. On the other hand, although traditional demodulation techniques has matured nowadays, but the demodulation technology which is available for high-dimensional modulation remains to be developed, especially the complex space mapping theory of the high-dimension modulation, which is different from the previous modulation technique. All of the above will add problems to the high-dimension demodulation. In order to solve the problems mentioned above, we have put forward the methods of choosing the constellation points, mapping and demodulation technology for the high-dimension modulation, which have the practical significance. The main works are as follows:Firstly, we make a detailed description for the proposed high-dimension modulation technique, and give the background and the basis of the high-dimension modulation technology. At the same time, the research results and the main research directions of the high-dimension modulation technology in recent years are illustrated in detail. Then we comb the developing venation of the high-dimension modulation technology at home and abroad in recent years, so that people have a preliminary understanding of high-dimension modulation technology.Then the basic concept and formula of high-dimension modulation are explained in detail, especially for the spectrum efficiency measuring the modulation format transmission capacity and transmission distance, and the asymptotic power efficiency. And we analyze the influence on high-dimension modulation deeply. Then we illustrate the four-dimension modulation technology widely studied in detail nowadays, including PS-QPSK, SP-QAM and POL-QAM,et, al. Then we classified the realization methods of high-dimension modulation, and explain the principle of high-dimension encoding and the ball filling theory to achieve the high-dimension modulation in detail. And we mainly focus on the sphere packing theory, and make an detail explanation from the generating of the sphere packing theory to the selection principle of the ball filled lattice point, as well as the commonly used lattice matrix. Then the basic model for high-dimension modulation system and the realization process for the high-dimension modulation are given.Secondly, aiming at the selection problems of space constellation points for the high-dimension, which we propose. We describe from the importance of lattice points. And we illustrate the reason why the lattice points selected points is necessary for the sphere packing high-dimension modulation technology. On the other hand, we give the principle and procedure of the lattice points theory based on the threshold. Then we apply constellation points selected by the lattice points to high-dimension modulation technique, producing high-dimension signal, which is analyzed in the simulation platform. Then we make a performance comparison between the constellation point selection algorithm based on the threshold and two high-dimension constellation point selection theory commonly used nowadays. And we get the advantages of our constellation point selection algorithm based on threshold.Again, we make a detail description for the basic theory of high-dimension mapping, and introduce several traditional mapping methods at the same time. Then we analyze the infeasibility of traditional mapping methods in high-dimension modulation system. According to the characteristics of high-dimension mapping, we have found that when applying ant colony algorithm in the QAP to high-dimension mapping, the demand of the shortest path in high-dimension mapping cost function can be well met. Then we introduce the basic principle of ant colony algorithm, as well as the realization of algorithm flow. And we verify the advantages of ant colony algorithm to achieve the high-dimension mapping in simulation, by using the BER curves of high-dimension mapping based on the gray mapping and ant colony algorithm mapping.Finally, the MMSE criterion is applied to high-dimension demodulation. Next, we give the BER curves and the eye-diagrams under the simulation system. All of the above make a full explanation the superiority of high-dimension modulation technique compared to conventional modulation technology in transmission performance.