Chinese civil satellite mobile communication application is now still in its infancy with its development direction, prospect of application and potential problems to be clarified. With these questions, we interviewed the former deputy director of Communication Department of General of Staff Headquarters, national famous satellite communication expert Yang Qianli during the ¡°Workshop on Satellite mobile communication and industrial development¡±.
Based on the lesson learned from the development of foreign mid/low earth orbit satellite mobile communication system and the actual condition of China, Geostationary satellite will be a more reasonable choice.
Chinese civil satellite mobile communication application is now still in its starting stage, would you please describe us the development direction of future satellite mobile communication system in China?
Judging from the development trend of relevant technology, satellite mobile communication technology as an important component of satellite technology set, develops with the improvement of the satellite functional capacity. We know that the larger the ERIP onboard the satellite, the larger is the power flux density so that terminals may receive signal of the same quality with smaller antenna. Ground terminal can get smaller with the satellite gets more powerful. Early communication satellites were relatively weaker in terms of power that required large antenna on the ground so that they could only to be used for international communication purpose in place of short wave equipments. When terminal antenna gets smaller as the increase of power of the satellite, satellite communication system starts serving the enterprises, households and there emerges the handheld satellite terminals.
There are two major directions of the development of satellite communication technology, one is high orbit scheme of large antenna, high power and multi-beam multiplexing, and the other one is low orbit scheme. The latter is more supeprior judging from the delay, the response time of the data link, and the propagation loss. European candidate satellite mobile communication proposals for the ITU 3G wireless mobile communication standardization process are mostly LEO schemes. But from a global point of view, the operation of LEO schemes seldom succeeds due to the problem of cost. When discussed with the CTO of Motorola on the failure of ¡°Iridium Satellite¡± system years ago, he claimed that the failure was not out of technical reason. It was in fact a quite advanced technology that the communication signal does not need to be transferred on the ground but to the recipient directly. It failed because of the misunderstanding of the market. Ground level wireless communication system was advancing dramatically at the time and gradually marginalized satellite mobile system from the metropolitan market to serve less populated areas with few potential users who can barely support the expensive commercial operating sys