中文摘要：

根据卫星的大范围，在广播网络的一颗卫星有各种各样的隧道状态。为了把一个有效无率的传播方法介绍给卫星多媒体广播 / 多点传送，与有限长度的包满足，一个跨层的包传播方法与为在网络层和低密度同等值的效率的变换(副) 代码检查的 Luby (LDPC ) 被建议为在物理层的可靠性的代码联合。从一个副编码器产生的 codewords 被划分成有限长度的包，它被一个 LDPC 编码器随后编码。基于噪音和卫星隧道的褪色的效果，也从一个 LDPC 解码器收到的 LT 包没有错误或是擦掉被标记，它能作为二进制代码被建模檫除隧道(BEC ) 。由副参数和 LDPC 参数上的理论分析，在 LDPC 之间的关系在物理层和副代码词编码率在网络层的长度被调查。与在 LT 代码词长度和 LDPC 代码率之间的折衷，优化了跨层的解决方案与一个二进制搜索算法被完成。由模拟验证了，跨层的参数设计的建议解决方案能根据卫星状态提供最好的传播模式，以便为卫星多媒体传播改进产量性能。

英文摘要：

According to large coverage of satellites, there are various channel states in a satellite broadcasting network. In order to introduce an efficient rateless transmission method to satellite multimedia broadcasting/multicast services with finite-length packets, a cross-layer packet transmission method is proposed with Luby transform （LT） codes for efficiency in the network layer and low density parity check （LDPC） codes for reliability in the physical layer jointly. The codewords generated from an LT encoder are divided into finite-length packets, which are encoded by an LDPC encoder subsequently. Based on noise and fading effects of satellite channels, the LT packets received from an LDPC decoder either have no error or are marked as erased, which can be mod- eled as a binary erasure channels （BECs）. By theoretical analysis on LT parameters and LDPC parameters, the relationships between LDPC code rates in the physical layer and LT codes word lengths in the network layer are investigated. With tradeoffs between the LT codes word lengths and the LDPC code rates, optimized cross-layer solutions are achieved with a binary search algorithm. Verified by simulations, the proposed solution for cross-layer parameters design can provide the best transmission mode according to satellite states, so as to improve throughput performance for satellite multimedia transmission.