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本文主要叙述VSAT—卫星网络类型及接入方式。从网络拓扑结构出发分析星形和网状两种网络形式、特点及通信业务。由中心站和若干个VSAT站组成的星形网络有三种通信方式:单跳、双跳和单、双混合式。在中心站的控制下,VSAT站之间通信要通过中心站经卫星线路实现,不能直接进行通信,线路延时较大,且通信业务受限。网状拓扑网络没有中心站,VSAT站之间可直接进行双向通信,线路延时小,在业务范围上也有新的突破。 VSAT网络接入方式极其重要,它决定着VSAT的性能,业务量及线路延时。不同的接入方式将影响卫星的利用率,信道容量的稳定性,结构的简易性,网络造价及组网灵活性等。据以上衡量标准,分别对TDM/FDMA、SCPC/FDMA、TDMA、CDMA和DAMA方式进行了分析,可根据用户不同的业务需求,组合并用,满足各种VSAT站灵活组网需要。
This article describes the VSAT-satellite network types and access methods. Starting from the network topology analysis star and mesh two forms of networks, features and communications services. There are three types of communication methods for a star network consisting of a central station and several VSAT stations: single hop, double hop and single and dual hybrids. Under the control of the central station, the communication between the VSAT stations should be realized through the central station via the satellite line, and the communication can not be performed directly, the line delay is large, and the communication service is limited. Mesh topology network does not have a central station, VSAT stations can be directly between the two-way communication, line delay is small, there are new business breakthroughs. VSAT network access is extremely important, it determines the VSAT performance, traffic and line delay. Different access methods will affect satellite utilization, channel capacity stability, structural simplicity, network cost and networking flexibility. According to the above measurement standards, the TDM / FDMA, SCPC / FDMA, TDMA, CDMA and DAMA modes are respectively analyzed, and various VSAT stations can meet the requirements of flexible networking according to different service demands of users.