Transmission Technologies In Integrated Mobile Satellite Service System

The rapid development of mobile communication requires higher network bandwidth, while the existing mobile network can’t satisfy the users’ need. The land mobile network faces severe problems, such as narrow coverage, higher costs in base station construction. Meanwhile, the satellite communication has the features of a nature broadcast, multicast and wide coverage. Even in terms of cost and technology, the cost performance and utilization rate are more excellent than the land mobile communication. Consequently, the broadband satellite communication network, which is reliable fast and stable, is a research hotspot.The Integrated Mobile Satellite Service System allows seamless inter-working and combine most powerful aspects of satellite and terrestrial network segments in a cooperative way. A fundamental advantage of combining satellite and terrestrial wireless components is that of efficiently extending network coverage, thus allowing connectivity in non-urban areas as well as supporting mobility for trains, ships, and planes. The emphasis of this paper is on how the Integrated Mobile Satellite Service System can be designed exploiting the cooperation of two segments in a seamless way. The main contributions of this paper include1. A discussion of the Integrated Mobile Satellite Service System modeling, the characteristics of satellite mobile channel and the most commonly used mobile satellite channel propagation models are summarized, such as Loo model, Fontan model, two-state model, dual-polarized MIMO channel model. The simulation of dual-polarized MIMO channel model in rural, suburban and urban areas in three different environments is carried out and capacity of the resulting dual-polarized2x2MIMO geostationary satellite mobile channel is obtained.2. The dedicated diversity scheme for Integrated Mobile Satellite Service system is proposed. Considering the Integrated Mobile Satellite Service system contains time diversity, space diversity, polarization diversity and frequency diversity, space-time coding and frequency coding with LSTBC structure is presented and the pairwise error probability is used to analysis the system performance. Using the space time code or space time frequency code, the cooperative transmission between satellite and ground station can achieve the overall diversity gain of8. In addition, the space time frequency codes can provide additional coding gain in frequency selective channel.3. Partial precoding for Integrated Mobile Satellite Service System unicast service is proposed, in which the ground station can obtain the channel state information from the feedback of users, then it optimize the precoding before it transmits the signals. Consequently, a better system performance is achieved. Both perfect and imperfect CSIT are investigated, and corresponding transceiver designs are proposed. Simulation results demonstrate that CSIT of the satellite channel can help dramatically improve system performance.