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最近几年来有许多卫星移动无线系统的方案问世,其中有些正趋于实现.在美国,联邦通信委员会(FCC)已促进工业界来实践这些可能的设计思想,而美国和加拿大的工业界也给予了积极的响应.最近,FCC已在UHF和L波段上分配了相应的频段,多数系统都提供电话和电报业务,而有些也提供无线测位或定位,因此就需要两颗或更多的有源卫星. 本文阐述了卫星移动通信与定位系统的现状,议题是频率选择、调制/多址的类型与系统设计,考虑有源与无源互调和多径干扰的影响. 还介绍了有关国内小规模移动通信系统的性能及定位分析,这里的卫星移动转发器仅是固定业务C波段或L波段有效负载的一部分,备用卫星的轨道位置由各种条件来控制,而不单单取决于无线定位. 本文提出的系统折衷方案及论证引出了一种信道容量高、测距精度好、抵制多路衰落能力强的调制/多址方式.
In recent years there have been many solutions for satellite mobile wireless systems, some of which are coming to fruition.In the United States, the Federal Communications Commission (FCC) has promoted industry to implement these possible design ideas, and the United States and Canadian industry have also given Recently, the FCC has allocated frequency bands on the UHF and L bands, most of which provide telephony and telegraphy services, while others also provide wireless location or location, thus requiring two or more Source satellite.This paper describes the status quo of satellite mobile communication and positioning system, the topic is the type of frequency selection, modulation / multiple access and system design, considering the impact of active and passive intermodulation and multipath interference.At the same time, The performance and positioning analysis of scale mobile communication systems where the satellite mobile transponders are only part of the C-band or L-band payload of the fixed service, the orbital positions of the spare satellites are governed by a variety of conditions, not just wireless positioning. The system compromise proposed in this paper leads to a modulation / multiple access scheme with high channel capacity, good ranging accuracy and multi-channel fading resistance.