Abstract: On-board processing (OBP) and asynchronous transfer mode (ATM) in satellite communication technology are considered as the development direction and core technology of future communication. In this paper, according to the current development of satellite communication technology, At the same time, it summarizes its key technologies and gives the direction of the future communication development, which is of great significance for the future research of satellite communications. Development Status and Difficulties of Satellite Communication System 1.1 Satellite Communication Development Status The development of satellite communication technology has been very rapid. In the 1960s, satellite communications were only applied to the military. By the 1970s, the development of satellite communications peaked. In the 1990s, optical fiber communications were born, which caused satellite communications However, the satellite has its own unique characteristics. For example, satellites have multiple access modes and can allocate bandwidth on demand. These are all beyond the scope of optical fiber communications. Therefore, satellite communications are used in remote areas and transoceanic communications Preferred. As the core part of satellite communication, satellite exchange is deeply researched by domestic and foreign scholars. The combination of satellite technology and ATM makes the satellite ATM technology become a research hotspot in the field of satellite. At present, many countries have carried out in-depth studies on satellite ATMs and expect to make a qualitative leap forward in the future. 1.2 Difficulties encountered in today's satellite communications (1) cost of satellite communications. As we all know, the most needed technology in long-distance communication is satellite communication, because satellite communication has the advantages of large communication capacity, wide geographic coverage, freedom from geographical conditions and flexible communication modes. However, the cost of satellite transponders has not changed as the cost of long-distance communications has dropped drastically since the adjustment of communication tariffs, thus making the cost of satellite communications very high. (2) Broadband IP in satellite communications. Currently, broadband IP satellite communications are basically ATM transmission technology, because the performance of ATM can meet the performance requirements of Europe and other places. However, when the system uses RS block coding, interleaving and FEC technology, although the satellite link transmission quality is improved, it also virtually increases the complexity of implementation of satellite ATM, which is different from the satellite communication technology currently in use . (3) Data rate in satellite communications. At present, the information age requires a more efficient way to transmit information in time. However, the traditional technology based on frequency division multiplexing and code division multiplexing can not meet the demand of satellite communications, and the packet switching technology appears at the same time. At the same time, the long The transmission of distance also brings the problem of delay, which needs to solve the influence of delay on real-time data through quick and effective method. 2 satellite communication system in the key technologies 2.1 data compression technology With the development of science and technology, data compression technology has developed very mature, especially in the field of data processing. Data compression can bring great convenience to communication, such as saving time, improving frequency band utilization and saving storage space. There are many data compression standards, but widely adopted standards are mainly the ISO standard for still image compression coding and the CCITT H.26 standard. The main use of satellite communications is MPEG62, the technology is mainly object-oriented, but also in the multimedia synchronization has played a very good role, while its real-time exchange, the implementation of performance and so has done a perfect. 2.2 smart antenna system Rainfall and the earth's absorption of electromagnetic waves have largely resulted in burst errors in high-band satellite ATM networks. Moreover, the satellite itself has various limitations and random errors, which need to be covered by multiple beams of smart antennas For example, a multi-beam fast-trip system may be used; at the same time, cellular antennas are used in low-orbital systems for tracking and co-frequency multiplexing; in order for satellite and synchronous orbit systems to form a cellular coverage map, Phased array antenna. 2.3 multiple access technology For access methods, ATM / TDMA multiple access methods are more suitable for satellite processing of multiple access requests than FDMA and CDMA, because this method has better information transmission perspective and network application flexibility. . However, TDMA requires high rate and transmit power, which virtually increases the difficulty of the demodulator and increases the ratio of carrier power to noise power density. In order to overcome the above problems, experts in this field propose a new way to adopt multi-frequency TDMA, that is, MF-TDMA (Multiple Frequency-TDMA) multiple access technology, which combines FDMA with TDMA to reduce The access rate for each TDMA link and the modem's operating rate are also reduced for the uplink value C / N0 (C / N0 = E / N0 * Rb). 2.4 Satellite Laser Communication Technology Satellite communications require high rates, which require laser communication. Satellite communications using lasers can improve the satellite traffic and confidentiality, reducing the weight and size of the satellite; in the atmosphere, there is no atmospheric interference, more accurate communication, but also reduces the error rate; the use of laser can enhance data transmission Speed ​​and system reliability; the same time, satellite communications do not interfere with each other, the most important is that the use of laser communications can significantly reduce the delay, so that information can be transmitted in time, these advantages are laser most vividly. Some experts predict that the application of laser technology to satellite communications will be very promising and will play an irreplaceable role in the development of the communications industry. 2.5 channel error correction coding technology It is well-known that mistakes are inevitable in satellite communications, especially during satellite communications. ATM cells make a big mistake in the face of burst errors. In ATM cells, the last byte located in the ATM header is the header error control (HEC), which protects the ATM header mainly by detecting and correcting single-bit errors and detecting if there are multiple bits. Therefore, in the event of missing cells or cell misplaceings, it is mainly because HEC did not play a role in multi-bit errors. Therefore, the interleaving technique is proposed to reduce the cell loss rate and the probability of detecting no error to protect the ATM header and improve the quality of information transmission. On-board ATM systems using MF-TDMA multiple access can provide different QoS services for different earth stations, with different QoS needs. 3 satellite communication system in the future development trend < 1 2 >