<p>&nbsp; &nbsp; &nbsp; &nbsp;随着下一个十年的到来，学术界和工业界都在积极展望第六代移动通信(The 6th Generation Mobile Communication, 6G)。据估计，在6G的移动业务中有八成以上的流量发生于室内。为应对新兴业务和流量消费的多样化发展，保证用户的差异化服务需求与信号的覆盖范围是深化室内通信亟需解决的关键问题。但常用的超密集组网和室内中继都面临着网络部署和运营成本过高的难题。因此，探索创新、节能的室内通信技术势在必行。在候选新技术中，可重构智能超表面(Reconfigurable Intelligent Surface, RIS)为扩展室内通信提供了新的方案。RIS不仅可以低成本的部署在室内，还能够通过调控信号波束来提升性能。在此基础上，本文结合RIS和波束赋形技术，解决了室内通信中差异化需求难以满足以及室内外通信中高频信号穿透损耗大、覆盖范围受限的问题。</p> <p>&nbsp; &nbsp; &nbsp; &nbsp;首先，针对室内通信中信号因墙壁和家具等障碍物发生折射、反射和扩散而经历较高的路径损耗，导致用户的差异化服务需求难以满足的问题，本文将透射型RIS作为智能辅助设备引入室内通信。在考虑室内静态、动态、自阻塞的情况下，以最小化接入点(Access Point, AP)的发射功率为目标，通过主被动波束赋形的联合优化来保证用户对信干噪比和有用接收功率的差异化需求。由于优化变量之间的耦合且优化问题中存在模为1的非凸约束，导致该优化问题非凸。本文提出了一种基于自适应惩罚函数的交替优化算法将复杂的优化问题分解为多个子问题并进行双层迭代求解，最终得到主被动波束赋形。仿真结果表明，在所考虑的仿真条件下，该算法的功率效率比固定RIS、退化的功率分配、传统中继算法和无RIS分别提高了48.7%、65.5%、69.1%、80.8%。</p> <p>&nbsp; &nbsp; &nbsp; &nbsp;其次，针对室内外通信中高频信号因建筑物墙体而造成穿透损耗大、覆盖范围不足的问题，室外BS利用可同时透射和反射的RIS(Simultaneously Transmitting and Reflecting RIS, STAR-RIS)来改善信号传输。在考虑室内/外阻塞与远近场信道对通信质量产生影响的情况下，以最大化最小用户信漏噪比(Signal to Leakage plus Noise Ratio, SLNR)为目标，在完成用户分组后联合优化基站(Base Station, BS)处的主动波束赋形和功率分配系数以及STAR-RIS处的被动波束赋形。由于该优化问题存在非凸约束和优化变量之间的耦合，采用基于自适应惩罚函数的交替优化算法对原问题进行等效转化和迭代求解。仿真结果表明，在所考虑的仿真条件下，所提算法的SLNR较固定RIS、随机分组、功率均分和非正交多址接入算法分别提高了1.8%、6.8%、18.3%、31.4%，而且在频谱效率方面也有2.6%~30%的提升。</p>

<p>&nbsp; &nbsp; &nbsp; &nbsp;With The arrival of the next decade, both academia and industry are positively looking ahead to The 6th Generation Mobile Communication (6G). It is estimated that more than 80% of the traffic in 6G mobile services takes place indoors. In order to cope with the diversified development of emerging services and traffic consumption, ensuring the differentiated service requirements of users and the coverage range of signals is a key issue that needs to be solved to deepen indoor communication. However, the common ultra-dense networking and indoor relay are faced with high cost of network deployment and operation. Therefore, it is imperative to explore innovative and energy-saving indoor communication technology. Among the new technologies configurable, Reconfigurable Intelligent Surface (RIS) provides a new mode for expanding indoor communication. RIS can not only be deployed indoors at low cost, but also improve performance by manipulating signal beams. On this basis, RIS and beamforming technology are combined in this thesis to solve the problems of difficult to meet the differentiated requirements in indoor communication and the high frequency signal penetration loss and limited coverage in outdoor to indoor communication.</p> <p>&nbsp; &nbsp; &nbsp; &nbsp;First of all, in order to solve the problem that signals in indoor communication experience high path loss due to the refraction, reflection and diffusion caused by obstacles such as walls and furniture, which makes it difficult to meet the differentiated service requirements of users, this thesis introduces the transmission RIS as an intelligent auxiliary device for indoor communication. In the case of indoor static, dynamic and self-blocking, the objective is to minimize the transmit power of Access Point (AP), and the joint optimization of active and passive beamforming can ensure the differentiated requirement for signal-to-noise ratio and useful receiving power of users. Due to the coupling between optimization variables and the non-convex constraint of module 1, the optimization problem is not convex. In this thesis, an alternate optimization algorithm based on adaptive penalty function is proposed to decompose complex optimization problems into multiple sub-problems and solve them iteratively by double-layer. The simulation results show that the power efficiency of the proposed algorithm is 48.7%, 65.5%, 69.1% and 80.8% higher than that of fixed RIS, degraded power allocation, traditional relay algorithm and No-RIS, respectively, under the simulation conditions.</p> <p>&nbsp; &nbsp; &nbsp; &nbsp;Secondly, aiming at the problems of large penetration loss and insufficient coverage caused by high frequency signals in outdoor to indoor communication due to building walls, Outdoor BS utilizes Simultaneously Transmitting and Reflecting RIS (STAR-RIS) to improve signal transmission. Considering the influence of indoor/outdoor blocking and near-far field channels on the communication quality, the aim is to maximize the minimum user Signal to Leakage plus Noise Ratio (SLNR). After user grouping, the active beamforming and power distribution coefficient at Base Station (BS) and passive beamforming at STAR-RIS are jointly optimized. Due to the non-convex constraint and the coupling between the optimization variables, the alternate optimization algorithm based on the adaptive penalty function is used for equivalent transformation and iterative solution of the original problem. The simulation results show that under the simulation conditions, the SLNR of the proposed algorithm increases by 1.8%, 6.8%, 18.3% and 31.4%, respectively, compared with the fixed RIS, random grouping, power averaging and non-orthogonal multiple access algorithms, and the spectral efficiency is also improved by 2.6%~30%.</p>

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