本书由北京交通大学和中兴通讯相关研究团队成员合作编写，兼具学术性和工程性的特点。本书阐述了多天线（Multiple-Input Multiple-Output，MIMO）技术的基本概念和未来发展方向，从基础理论、关键技术、工程问题等方面阐述了面向 5G-Advanced 和 6G 的大规模 MIMO（Massive MIMO）、去蜂窝大规模 MIMO（Cell-Free Massive MIMO）和智能超表面（Reconfigurable Intelligent Surface，RIS）技术。 本书深入浅出、概念清晰，可作为去蜂窝大规模 MIMO 及 RIS 技术研究人员的参考资料，也可以作为 6G 研究同行的技术指导资料，还可以作为对 6G 感兴趣读者的技术读物以及高年级硕士生和博士生的学习资料，并为未来 6G 商用的技术选择和决策提供参考。

多天线（Multiple-Input Multiple-Output，MIMO）技术已有很多年的发展过程，从 3G的 TD-SCDMA 中的智能天线，到 4G LTE 中 OFDM 与 MIMO 的完美结合，再到 5G 中大规模 MIMO 收发天线规模的数量级扩展，MIMO 技术已经成为无线通信系统最关键的空口技术之一。MIMO 技术发展包括不断增加集中式天线规模来提升空间复用增益和阵列增益，例如，天线规模从 2Tx、8Tx 到 256Tx；或者采用分布式多天线，体现为网络 MIMO(Network MIMO）、分布式 MIMO（Distributed MIMO）、多点协作发送（Coordinated Multiple Points），直至打破蜂窝小区限制的去蜂窝 MIMO（Cell-Free Massive MIMO）技术。可以预期，在 5G-Advanced 和 6G 标准中，MIMO 技术将会进一步发展，作为提升频谱和能量效率的关键技术之一，受到学术界和工业界专家的广泛关注。 智能超表面（Reconfigurable Intelligent Surfaces，RIS）技术作为一种近年来新涌现的技术，作为可编程二维超表面，具有无源调控、低成本、易部署等独特的技术特性。RIS技术虽然可以部分地借助传统 MIMO 理论进行分析研究，但已不是传统 MIMO 技术的范畴，而是一种全新的技术概念。简单的 RIS 技术有机会在 5G 网络中初步标准化及商业化应用，以增强 5G 网络性能；先进的 RIS 技术则可以在未来 6G 网络中构建智能可控无线环境，引入全新的网络范式。 迄今为止，市场上尚未有系统阐述 MIMO 技术演进及 RIS 技术的专业书籍，因而从事此领域技术研究、产品开发等相关技术人员难以有合适的资料参考学习，这显然不利于此领域的发展。恰在此时，电子工业出版社向笔者约稿规划一套 5G/6G 相关的技术丛书，且中兴通讯与北京交通大学团队在此领域已有多年的紧密合作和技术研究积累，因此规划并着手撰写此书。计划利用此书对 MIMO 技术演进及 RIS 技术进行系统阐述，主要包括三方面内容：①传统 MIMO 技术增强与演进；②对 MIMO 技术重要的演进方向去蜂窝 MIMO 技术进行重点探讨；③对 MIMO 的全新技术范式性——RIS 技术的概念、关键技术及应用场景进行初步探讨。 参与本书撰写的主要成员分别来自高校学术研究团队和企业工程应用研究团队，在MIMO 技术和 RIS 技术领域有着较多的研究积累和工程化应用经验。联合撰写团队计划发挥各自在学术和工程化的多年积累的优势，力图从学术性和工程化两方面紧密结合，提供给读者一本同时兼具两方面特色的专业技术图书。 本书由章嘉懿和向际鹰统稿。具体章节撰写分工如下：赵亚军负责前言和第 1 章绪论，向际鹰和孟溪负责第 2、3 章，章嘉懿负责第 4、5、6 章，菅梦楠负责第 7 章，刘睿祺负责第 7 章部分内容的撰写，禹宏康负责部分内容的补充校对。感谢东南大学金石教授、北京交通大学艾渤教授和中兴通讯崔亦军总工对本书的指导，同时感谢北京交通大学范婧怡、陈帅飞、郑家康、王者、史恩宇、张京、刘恒、金宇、张永顺等同学对本书的贡献，特别感谢中兴通讯高级副总裁张万春专门为本书作序。 本书中引用了不少论文、专业书籍等文献中的技术观点，在此对相关作者表示感谢。同时，本书也引用了一些标准协议，由于标准协议可能会进一步更新，若想了解最新版本，请参考相关标准网站。另外，本书部分文字借鉴了网络上一些技术博客、专业网站等的描述，不便一一罗列，特别在此表示感谢。 鉴于时间仓促，加之作者水平有限，不妥及错误之处在所难免，恳切希望读者给予批评指正。 本书为“新一代通信技术系列丛书”中的一本，本书策划与撰写工作得到了“国家宽带移动通信多媒体实验室”和“轨道交通控制与安全国家重点实验室”的大力支持。另外，撰写本书的主要作者为工业和信息化部重大专项“5G 多天线接口融合架构及关键技术研发、试验与验证”、科技部重大专项“6G 频谱共享技术”和科技部重点研发计划“6G 无线空口传输技术”的骨干成员，文中涉及的关键技术部分来自上述项目的研究成果。在此，分别对上述机构及项目的支持表示特别感谢！

第 1 章 绪论····················································································································1 1.1 引言·····························································································································1 1.2 从多天线技术演进到全新智能超表面技术·······························································4 1.3 内容概述及章节结构··································································································5 第 2 章 蜂窝大规模 MIMO 技术 ····················································································.6 2.1 序言·····························································································································6 2.1.1 MIMO 技术的发送和接收 ··············································································6 2.1.2 MIMO 参考信号设计······················································································8 2.1.3 信道信息获取方式 ··························································································8 2.2 基础理论 ·····················································································································9 2.2.1 蜂窝大规模 MIMO 空间复用技术··································································9 2.2.2 蜂窝大规模 MIMO 空间复用模型································································13 2.2.3 蜂窝大规模 MIMO 信道状态测量································································15 2.3 蜂窝大规模 MIMO 设计···························································································17 2.4 蜂窝大规模天线多用户复用技术 ············································································18 2.4.1 多用户数据传输问题 ····················································································19 2.5 波束管理 ···················································································································20 2.5.1 多用户 MIMO 中在获知干扰情况下的波束管理 ········································20 2.5.2 以人工智能为基础的波束管理·····································································22 2.6 虚拟扇区化 ···············································································································24 第 3 章 蜂窝大规模 MIMO 技术挑战与应用 ··································································28 3.1 多小区协作机制········································································································28 3.2 蜂窝大规模 MIMO 技术对网络架构的影响 ···························································28 3.2.1 蜂窝大规模 MIMO 天线阵列配置的位置····················································29 3.2.2 异构网络下同频与异频方案·········································································29 3.2.3 异构网络下双工方式选择·············································································31 3.3 降低信道测量开销技术····························································································31 3.3.1 利用压缩感知降低开销技术·········································································31 3.3.2 分维反馈降低开销技术·················································································32 3.4 非信道互易场景的大规模 MIMO 技术 ···································································33 3.4.1 非信道互易性问题分析·················································································33 3.4.2 非信道互易场景下大规模 MIMO 技术应用分析 ········································36 3.4.3 接收端 MIMO 技术应用 ···············································································37 3.5 蜂窝大规模 MIMO 有源阵列应用···········································································38 3.6 蜂窝大规模天线 MIMO 技术与高频段传输的结合················································40 3.7 本章小结 ···················································································································40 第 4 章 去蜂窝大规模 MIMO 技术·················································································41 4.1 序言···························································································································41 4.2 去蜂窝大规模 MIMO 的发展···················································································44 4.3 基础理论 ···················································································································47 4.3.1 系统架构与特点 ····························································································47 4.3.2 用户为中心的系统模型·················································································49 4.3.3 信道模型········································································································51 4.3.4 信道硬化和信道正交 ····················································································54 4.4 本章小结 ···················································································································55 第 5 章 去蜂窝大规模 MIMO 关键技术··········································································57 5.1 导频分配策略 ···········································································································57 5.1.1 基于图染色理论的导频分配·········································································58 5.1.2 基于禁忌搜索的导频分配·············································································61 5.2 信道估计方法 ···········································································································64 5.2.1 基于导频训练的信道估计·············································································64 5.2.2 基于深度学习的信道估计·············································································67 5.3 联合信号检测 ···········································································································73 5.3.1 大尺度衰落解码 ····························································································74 5.3.2 全导频迫零接收机 ························································································77 5.3.3 部分全导频迫零接收机·················································································78 5.3.4 保护弱用户的部分全导频迫零接收机 ·························································80 5.3.5 分布式正则化迫零接收机·············································································82 5.3.6 局部大尺度衰落解码 ····················································································88 5.3.7 最优双线性均衡器 ························································································89 5.4 功率控制算法 ···········································································································93 5.4.1 启发式功率控制 ····························································································94 5.4.2 基于凸优化方法的功率控制·········································································96 5.4.3 基于深度学习的功率控制·············································································99 5.4.4 功率控制算法对比 ······················································································102 5.5 本章小结 ·················································································································105 第 6 章 去蜂窝大规模 MIMO 系统的工程问题·····························································106 6.1 前传容量压缩 ·········································································································106 6.1.1 基于前传链路受限的传输机制···································································106 6.1.2 基于低精度 ADC 的前传容量压缩····························································.114 6.1.3 基于深度学习的前传容量压缩··································································.116 6.2 基于相位噪声的系统性能分析 ·············································································.118 6.3 基于硬件损伤的系统性能分析 ··············································································120 6.4 基于 NOMA 的去蜂窝大规模 MIMO 系统分析 ···················································125 6.5 基于联邦学习的去蜂窝大规模 MIMO 系统 ·························································129 6.6 基于可扩展性的去蜂窝系统设计 ··········································································131 6.7 基于分布式空间部署的同步问题 ··········································································135 6.8 去蜂窝大规模 MIMO 技术展望·············································································135 6.9 本章小结 ·················································································································138 第 7 章 智能超表面技术······························································································140 7.1 概述·························································································································140 7.2 RIS 优势与应用分析 ······························································································144 7.3 信道模型分析 ·········································································································146 7.4 信道模型分析 ·········································································································152 7.5 波束赋形设计 ·········································································································154 7.6 RIS 与多种技术结合分析·······················································································156 7.6.1 物理层安全··································································································156 7.6.2 感知定位······································································································157 7.6.3 基于 NOMA 的 RIS 辅助通信系统·····························································158 7.7 未来挑战分析 ·········································································································159 7.8 拓展阅读：RIS 标准与产业推动进展 ···································································162 参考文献·······················································································································165