论文中文题名: | 分布式MIMO系统天线阵列拓扑与AP部署优化研究 |
姓名: | |
学号: | 21207040040 |
保密级别: | 公开 |
论文语种: | chi |
学科代码: | 081002 |
学科名称: | 工学 - 信息与通信工程 - 信号与信息处理 |
学生类型: | 硕士 |
学位级别: | 工学硕士 |
学位年度: | 2024 |
培养单位: | 西安科技大学 |
院系: | |
专业: | |
研究方向: | 无线通信 |
第一导师姓名: | |
第一导师单位: | |
论文提交日期: | 2024-06-12 |
论文答辩日期: | 2024-06-04 |
论文外文题名: | Research on antenna array topology and AP deployment optimization for distributed MIMO systems |
论文中文关键词: | |
论文外文关键词: | Distributed MIMO ; Access Point ; ergodic sum rate ; subarray antenna layout ; AP location deployment |
论文中文摘要: |
分布式MIMO(Distributed MIMO, D-MIMO)系统由于具有覆盖范围更广、分集增益更高、提高系统容量和降低传输功率等特性,有望成为新一代移动通信系统的关键使能技术之一。然而,在分布式MIMO系统中,如何合理优化接入点(Access Point, AP)的部署以及AP上子阵列的拓扑结构设计,是影响系统性能的关键问题。分布式MIMO系统通过AP子阵列进行数据传输,天线阵列的研究正向着稀疏阵列发展。将稀疏阵列与分布式MIMO技术相结合起来运用,可以进一步提升系统性能。鉴于用户频谱效率则是系统性能的关键指标,本文从优化系统用户频谱效率出发,研究了多个AP的位置部署与天线阵列拓扑优化,具体研究内容包括: (1)针对多用户分布式MIMO系统下行传输场景,以最大化用户遍历和速率为目标,提出一种基于AP子阵天线布局优化的方法。具体来说,在多个AP配置相同天线阵列拓扑结构,为用户提供服务的下行传输场景中,建立了毫米波信道模型,并假定AP位置是固定的。以系统遍历和速率为优化目标,以天线阵元位置排布为优化变量,同时满足相邻阵元最小间距和阵元孔径的约束条件,从而建立了固定AP位置下子阵阵列拓扑的数学优化问题;根据所建数学模型,借助詹森不等式、Mullen不等式和大数定律等推导出目标函数的近似表达式,并对优化问题进行转化。利用泰勒展开和连续凸近似求解固定AP位置下的子阵拓扑优化问题。数值仿真结果表明,优化后的子阵拓扑为两边稀、中间密的(Non-Uniform Linear Array, NULA)NULA拓扑,其系统性能显著优于子阵拓扑为均匀阵列拓扑的方案。与其他几种子阵天线拓扑方案相比,所提出的子阵天线布局优化方案显著提高了系统和速率。 (2)在分布式MIMO通信系统中,为了更加贴近实际应用场景,需要考虑多AP位置部署优化问题,因此,在多用户D-MIMO系统中,通过联合优化多AP的位置部署与天线阵列拓扑,系统遍历和速率最大化。具体而言,考虑AP子阵天线布局使用均匀平面天线阵列,并假定在固定区域内部署AP位置,将系统遍历和速率作为优化指标,设计子阵天线拓扑与AP位置部署的优化方案。由于遍历和速率表达式中含有期望项,不易直接处理,借助詹森不等式来推导其近似表达式,再对优化问题进行转化处理与求解,最终利用迭代算法获得最优的阵列拓扑结构与多AP的位置部署。数值仿真结果验证了所提方案相比于基准部署方案可获得更高的系统遍历和速率,优化后的子阵拓扑呈现稀疏阵列特征,表明AP位置部署和子阵拓扑优化的必要性。 |
论文外文摘要: |
Distributed MIMO ( D-MIMO ) system is expected to become one of the key enabling technologies for the new generation of mobile communication systems due to its wider coverage, higher diversity gain, higher system capacity and lower transmission power. However, in distributed MIMO systems, how to reasonably optimize the deployment of Access Points ( Aps ) and the topology design of subarrays on APs is a key issue that affects system performance. The distributed MIMO system transmits data through AP subarrays, and the research of antenna arrays is developing towards sparse arrays. Combining sparse array with distributed MIMO technology can further improve system performance. In view of the fact that user spectrum efficiency is a key indicator of system performance, this paper studies the location deployment of multiple APs and the topology optimization of antenna array from the perspective of optimizing the spectrum efficiency of system users. The specific research contents include : (1) Aiming at the downlink transmission scenario of multi-user distributed MIMO system, a method based on AP subarray antenna layout optimization is proposed to maximize the user ergodic sum rate. Specifically, in the downlink transmission scenario where multiple APs are configured with the same antenna array topology to provide services to users, a millimeter-wave channel model is established and the AP position is assumed to be fixed. Taking the ergodic sum rate of the system as the optimization objective, the position arrangement of the antenna array elements as the optimization variable, and satisfying the constraints of the minimum spacing between adjacent array elements and the aperture of the array elements, the mathematical optimization problem of the subarray topology under the fixed AP position is established. According to the mathematical model, the approximate expression of the objective function is derived by means of Jensen inequality, Mullen inequality and the law of large numbers, and the optimization problem is transformed. The Taylor expansion and continuous convex approximation are used to solve the subarray topology optimization problem with fixed AP position. The numerical simulation results show that the optimized subarray topology is a Non-Uniform Linear Array ( NULA ) NULA topology with sparse on both sides and dense in the middle, and its system performance is significantly better than that of the subarray topology with uniform array topology. Compared with other subarray antenna topology schemes, the proposed subarray antenna layout optimization scheme significantly improves the system sum rate. (2) In the distributed MIMO communication system, in order to be closer to the actual application scenario, it is necessary to consider the multi-AP location deployment optimization problem. Therefore, in the multi-user D-MIMO system, the system ergodicity and rate are maximized by jointly optimizing the location deployment and antenna array topology of multiple APs. Specifically, considering that the AP subarray antenna layout uses a uniform planar antenna array, and assuming that the AP location is deployed in a fixed area, the system traversal and rate are used as optimization indicators to design the subarray antenna topology and AP location deployment optimization scheme. Because the ergodic sum rate expression contains the expected term, it is not easy to deal with directly. The approximate expression is derived by means of Jensen inequality, and then the optimization problem is transformed and solved. Finally, the iterative algorithm is used to obtain the optimal array topology and the location deployment of multiple APs. The numerical simulation results verify that the proposed scheme can obtain higher system ergodic sum rate than the benchmark deployment scheme, and the optimized subarray topology presents sparse array characteristics, indicating the necessity of AP location deployment and subarray topology optimization. |
参考文献: |
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中图分类号: | TN92 |
开放日期: | 2024-06-13 |