星地融合网络中基于层分复用的广播和单播传输鲁棒波束赋形

星地融合网络(STIN)为解决下一代无线通信中地面基站存在的覆盖范围约束和频谱短缺瓶颈提供一种有效架构。针对该融合网络中下行广播和单播单独传输性能受限问题，该文建立基于服务质量(QoS)约束的最小化传输功率优化模型，提出基于层分复用(LDM)的鲁棒联合波束赋形传输方案。且根据最差情况准则，采用S-Procedure及半正定松弛(SDR)方法将具有无穷维约束的鲁棒优化问题转化为具有线性矩阵不等式(LMI)的确定性优化形式，并提出一种基于罚函数的迭代算法求解该问题。仿真结果表明，所提方案在传输功耗方面比传统正交时分复用(TDM)传输方案降低约6 dBm，且用户平均速率相较于非协作传输方案提升明显。

Robust Beamforming for Layer Division Multiplexing Based on Broadcast and Unicast Transmissions in Satellite-Terrestrial Integrated Networks

The Satellite-Terrestrial Integrated Networks (STIN) is able to provide an effective framework to solve the limitation of coverage and spectrum shortage of terrestrial base station for the next generation wireless communication. Considering the performance limitation of downlink broadcast and unicast standalone transmission in STIN, an optimization problem that minimize the transmit power based on Quality of Service (QoS) constraints is established, and a robust joint beamforming transmission scheme based on Layer Division Multiplexing (LDM) is proposed. According to the worst-case criterion, the robust optimization problem with infinite-dimension constraints is transformed into a deterministic optimization form with Linear Matrix Inequality (LMI) by employing S-procedure and Semi-Definite Relaxation (SDR) methods. And then, an iterative algorithm based on penalty function is also proposed to address the original problem. Simulation results show that, the power consumption of the proposed algorithm is about 6 dBm lower than traditional orthogonal Time Division Multiplexing (TDM) transmission scheme, while the cooperative transmission scheme outperforms significantly the non-cooperative ones in terms of the average user rate.