New Approach Of Improving The Transmission Efficiency On Satellite Communication Channel

Through the development of more than half of the century, satellitecommunication which proposed in 1940s has growing up into an important new wayused in regional and international communication, national basic trunkcommunication, defense and military communication, industry and enterprise, evenpersonal communication and so on. As we enter the 21st century, with the rapiddevelopment of our Telecom industry and the widely use of optic Fiber circuit, thegrowing ground communication capacity and the cost decreasinging on groundcommunication, satellite communication industry faces more and more competitionpressure. The expensive leased charge on transponder bandwidth has always obstacledsatellite communication in wide use. It is the concerning problem of subscriber thathow to improve the transmission efficiency on satellite transponder bandwidth, howto fully utilize the limited and precious satellite frequency and power resource, how toreduce the charge on transponder bandwidth as possible.Kinds of new satellite communication channel coding andmodulation/demodulation technology based on VSAT system design involving VSATcommunication transmission technology have been discussed in the article as well asits basic principle and application in satellite communication. In digit modulation,signal transmission quality mainly hinges on Bit Error Rate(BER), so that, on thesame ratio value of the signal energy per bit and noise power spectrum density, thelower BER modulating method is , the lesser the satellite power is required;inadditional, to save the precious satellite band, utilization of frequency band shall behigh as possible. Experiment and detailed performance contrast between kinds of FECcoding and modulation/demodulation technology is included in the article.A lasted new technology on Two-way satellite communication system is studiedin the article, that is , Paired Carrier Multiple Access (PCMA) technology, it is alasted new method of frequency multiplexing in satellite communication system,PCMA technology is completely compatible with the existing satellite communicationsystem and kinds of multiple access(FDMA, TDMA, CDMA). It is independent of themodulation , FEC and any bit stream protocol, and has no influence on the existingcommunication system, so, it cannot substitute any FEC coding,modulating andmultiple access technology, it must be used to gether with a variety of modulating,FEC and multiple access technology. PCMA equipment operates between existingsatellite MODEMs and up/down converters, or it is seted inside the MODEM.PCMA can decrease the bandwidth required of the existing satellite communicationsystem by 50%. PCMA basic principle, technology reality, performance testing,features of PCMA and finally the performance analysis and application prospect isdescribed in the article.