Research On Transmission And Access Technology Of Space-ground Integrated Network

The air space ground integrated information network is proposed to provide an effective way, which that has become a worldwide research hotspot and the basic trend. The airspace ground integrated information network architecture includes satellite backbone network, deep space communication network, and stratospheric communication network and information transmission between different layers of network. In this paper,we research and analyze air space ground integrated information network system architecture and the key technology related to ground optical communication, inter satellite optical communication and satellite ground laser communication in the architecture. The main works are as follows:1. This paper introduces the design of the constellation model of MEO and LEO and the single layer network topology composed of each layer of nodes, and discusses the satellite network architecture composed of three layers of nodes. In this paper, we simulate constellation coverage characteristic simulation by using 3 GEO satellites, 12 MEO satellites and 36 LEO satellites to form a GEO/MEO/LEO three layer for the whole day in global. The design of three layer satellite network can achieve a cycle in 100% global coverage and to meet the goal of switching time is longer in the paper , to meet the design target of the constellation we use less overall satellite number and simple constellation structure.2. The scheme of "no uniform design of the optical fiber channel mapping proportion" is proposed, to reduce the inter core coupling with the optical fiber transmission with fewer crosstalk and higher transmission efficiency by designing the fiber core parameters reasonable and adjusting the various core structure layout. On this basis, to build space division multiplexing optical transmission system based on few-mode multicore fiber, by simulating and analysis the channel characteristics and transmission characteristics, we can realize the large capacity and long haul optical fiber transmission through the reasonable design parameters of optical fiber and the fiber core reasonable layout. In further, seven core fiber link is proposed, we discuss the influence of crosstalk and attenuation factors on the performance of the link through theoretical analysis and numerical simulation, and also we put forward the MIMO equalization algorithm based on the transfer matrix for signal processing of DSP, to reduce the error rate which is desired effect. Finally, the large capacity long distance T bit DS transmission experiment is completed, and we analyze the system error rare in different modulation formats and system parameters performance is compared.3. In this paper,The star laser communication and signal transmission in the classic error control codes are introduced, we design a new modulation and coding format LDPC-TCM-MQAM by establishing a link model FEC by coded modulation(TCM)technology, before to error correction coding (LDPC) and high order modulation (MQAM)combination. we obtain the coding gain more than 2dB through atmospheric channel transmission of the coded modulation scheme by simulation, and the receiving end the constellation diagram and eye diagram can be seen the coding performance is stable, the accept signal has good quality ,which can be applied in the atmospheric channel satellite optical communication transmission system.4. We put forward the multimode and high stable reference spectral technology and satellite collaborative adaptive frequency conversion technology based on spectrum sensing technique of photonic microwave,which is realized low cost and no distortion of the photon on conversion and photonic down conversion. And based on the sweep frequency filtering and coherent light two schemes of photonic sensing ultra wideband spectrum detection technology, we obtain the power spectrum distribution of information to realize the spectrum detection. In addition we can get more accurate and stable spectrum sensing results by setting a reasonable threshold, thus solve to the problems of electric field sensing bandwidth is too narrow, perception rate is too low, the high frequency component of preparation and difficulty of integration of large effective, and reduce the cost while achieving the microwave signal high-speed effective spectrum sensing and management optimization greatly.