Study On Mode Division Multiplexing Based On High Dimensional Modulation

With the development of the global communications network data transmission technology, some streaming media services such as HDTV, online broadcast, distance education, people’s lives will become indispensable parts in the near future. Moreover, cloud computing, online games(including Cloud games), video chat, social networking, blog, file sharing, etc. began to enter people’s lives. Now the demand for bandwidth is growing,bandwidth in the near future will reach saturation.In order to avoid the situation of "capacity crunch", a variety of technology such as Wavelength Division Multiplexing(WDM), Polarization Division Multiplexing(PDM) and Orthogonal Frequency Division Multiplexing(OFDM) have been proposed. However, most of these technologies are based on Single Mode Fiber Communication System.The capacity of SMF is sestricted by the nonlinear effects and amplifier spontaneous emission noise inherent, making the system more and more close to the Shannon capacity limit. To this end, it has proposed a new expansion technique—mode division multiplexing. The basic idea of mode division multiplexing is use less mode fiber’s orthogonal mode to transmission information, so exponentially increases the transmission capacity of the system. At the same time, high dimensional modulation technique because of its high spectral efficiency and progressive power efficiency into the researchers’ sight. High dimensional modulation no longer like a traditional modulation format as in two dimensions optimized, high dimensional modulation signal in space as a whole, such as four-dimensional modulation in four-dimensional space is optimized, that is, two orthogonal polarization states and quadrature-phase component, and it can not be decomposed into two separate two dimension signal. From signal modulation techniques and transmission capacity of the transmission system both to improve transmission performance, this paper attempts to combine mode division multiplexing and high dimensional modulation technology. Specific work are as follows:Firstly, introduction the basic structure of the mode division multiplexing system, discusses the components of the system architecture. Then discusses the three key mode division multiplexing techniques of communication, which are few-mode fiber technology, mode division multiplexing / de-multiplexing technology and signal processing technology.Secondly, it discusses the basic principles of high-dimensional modulation techniques. Details of the three methods to produce high-dimensional modulation signal: the time domain mixing process, the coding method and sphere packing method, and introduction the two key technology for high-dimensional modulation: constellation point selected technology and mapping technology into details. Finally, the system block diagram of the high-dimensional modulation, the establishment of high-dimensional simulation system modulation.Again, produce the desired high dimensional modulation signal use the technology of mentioned in Chapter III constellation points selected technology and mapping technology, according to the principle of the mode division multiplexing system, establishment of a high dimensional modulation mode division multiplexing system. Then from the SNR, length and anti-coupled three aspects simulation based on high modulation mode division multiplexing system advantage.Finally, research the high-dimensional modulation mode division multiplexing system’s signal processing technology. Frequency domain compensation method for compensating chromatic dispersion, using constant modulus algorithm,compensated polarization mode dispersion, using independent component analysis algorithm compensation the injuries caused by mode coupling, Analysis the performance before and after the algorithm use.