卫星交换-码分多址技术

Satellite-switched code-division multiple access techniques

星上交换是我国下一代卫星通信发展的重要方向 .文中研究了卫星交换 /码分多址 (SS/CDMA)技术 ,重点放在码分交换 (CDS)技术的基本原理、性能特点和技术关键 .SS/CDMA系统能为多波束对地静止卫星的固定业务提供多址和交换功能 ,该系统上行接入采用CDMA ,下行采用码分复用 ,星上交换采用码分交换 ,整个系统采取按需分配控制 .在码分交换中 ,需对解扩后的业务信号进行再扩频 (respread)、过扩频 (overspread)处理 .CDS模块是一种无阻塞结构 ,在交换结点处不需要解调 /再解调、信道解码 /再编码、信源解码 /再编码和数据缓存 .文中提出了如何推进这一技术广泛应用的几点建议 .

Onboard switching is a very important direction of developing the next generation of satellite communication systems in our country. This paper studies a satellite-switched CDMA technique, with emphasis on the principles, characteristics and key issues of the code-division switch technique. An SS/CDMA system can provide both multiple access and switching to a multibeam geostationary fixed satellite service. The uplink access method is based on CDMA, the downlink on code-division multiplexing (CDM), and the onboard switching on code-division switching (CDS). The system operates with demand assignment control. In the CDS, the traffic signals despreaded will be respread and overspread. The CDS fabric is nonblocking, and it does not require demodulation/remodulation, channel decoding/reencoding, source decoding/reencoding and data buffering at the switch node.