无线接入回传一体化关键技术及标准化进展

为实现小区密集部署,减少对有线传输基础设施的需求,3GPP Rel-16引入5G新空口(NR)无线接入回传一体化(IAB)技术,定义了独立组网和双连接的网络架构,引入同一 IAB收发资源的时分复用满足半双工需求.3GPP Rel-17标准化了IAB增强技术,首先进一步引入了频分复用和空分复用的资源复用方式,实现多种复用...     

面向5G-Advanced无线系统的高精度定位技术

随着定位技术的快速发展，面向5G-Advanced的高精度定位技术正受到越来越多的关注。首先，介绍了第三代合作伙伴计划（3rd Generation Partnership Project,3GPP）Rel-16和Rel-17的5G定位标准现状和Rel-18的5G-Advanced定位技术增强方向。其次，重点研究了5G正交频分复用（orthogonal frequency division multiplexing,OFDM）信号模型和载波相位定位技术需要解决的3个关键算法：基于锁相环的载波相位测量算法、基于参考终端的双差分算法和基于拓展卡尔曼滤波的用户设备（user equipment,UE）位置解算算法。最后，分析了低功耗高精度定位技术方案和基于定位参考设备的定位精度增强技术方案。     

多载波HSPA技术及其演进

为了进一步提高HSPA系统的峰值数据速率以及用户吞吐量,3GPP在Rel-8中引入了双载波HSDPA（highspeeddownlinkpacketaccess．高速下行分组接入）技术。这种双载波技术既可以实现很高的资源利用率又可以减小频率选择性带来的影响从而使得信道条件较差的用户可以获得更好的性能。为了满足宽带移动通信业务的需求,3GPP在Rel-10中又引入了4载波HSDPA技术。本文首先阐述了多载波HSPA技术的演进过程,然后介绍了各种多载波HSPA技术及其研究热点,并且分析了多载波技术对网络架构和用户设备的影响,最后介绍了多载波HSPA技术的研究现状。     

3GPP新空口定位技术及其性能

文章介绍了3GPP新空口(NR)定位的需求、网络架构、和Rel-16关键定位技术,然后基于3GPP评估方法给出了定位性能的评估。     

多接入、无线、有线融合架构演进及流量调度机制

3GPP 5G网络架构在3GPP Rel-16版本定义了无线有线融合架构,即固移融合网络架构,并重点研究此融合架构下的多个价值场景。其中,有线与无线混合接入场景备受关注,同时3GPP标准定义了此场景下的多接入流量调度机制。对此进行了详细论述,包括基本的多接入流量调度机制、增强5G-Adanced网络支持UDP业务流和以太业务流的包粒度分流机制以及新的冗余传输模式,并扩展4G和5G互通场景以支持3GPP接入5GC和非3GPP接入EPC的混合网络流量调度。     

5G-Advanced网络的位置服务与关键技术

3GPP制定的5G标准Release 15(Rel-15)版本仅支持紧急业务的位置服务需求,在Rel-16完成了5G位置服务网络架构、网元功能、端到端流程设计、定位参考信号、测量量、测量流程等的标准化后,成为了支持商业场景位置服务的完整版本。Rel-17则进一步缩短了定位服务时延、提升了定位精度到米级。3GPP在2022年开始Rel-18位置服务和定位研究项目,主要包含进一步提升定位性能指标（如更低时延、更高精度和更低能耗）,以及进一步扩展定位功能（如支持Sidelink定位、用户面定位和卫星接入场景的终端位置验证等）。在介绍Rel-15/Rel-16/Rel-17位置服务研究进展的基础上,提出、分析了实现Rel-18定位的部分潜在关键技术,指出了6G网络的定位需求是更高的精度、支持更高速度场景的定位、支持更多的垂直行业和场景,人工智能、太赫兹通信将成为实现6G更高精度定位的潜在关键技术。     

面向6G的星地融合标准化研究进展

星地融合被视为6G的标志性发展方向,ITU和3GPP等国际标准化组织或其它机构正有序推进面向6G的星地融合标准研发。对具有全球代表性的面向6G的星地融合标准化研究机构进行了简单介绍,重点分析ITU和3GPP在5G-Advanced及6G标准化过程中关于星地融合的主要研究和标准化成果。ITU在对卫星在IMT-2020网络的用例、场景、能力、系统、无线电接口,以及性能参数等方面进行了规范的同时,在IMT-2030未来技术趋势有关建议书突显了卫星的地位与作用。3GPP在冻结全球首个5G非陆地网络标准Rel-17、确立NR-NTN规范之后,于Rel-18版本中优化NR-NTN的同时,推出E-UTRA-NTN,并已启动Rel-19研发工作,有望在2026年启动6G标准研发。对中国IMT-2030(6G)推进组在推动6G星地融合标准化方面所做出的积极贡献一并进行了介绍,并对6G星地融合标准化工作进行了总结和展望。     

5G-NR蜂窝系统功能演进趋势分析

3GPP Rel-15版本规范为5G-NR系统奠定了最基本的系统功能集合和部署工作方式,主要实现了超宽带eMBB类和高可靠低延时URLLC类基本业务和应用。之后的Rel-16版本引入了许多增强的系统特征功能,更多地强化eMBB和URLLC类的业务应用性能。Rel-17旨在面向和5G相关的更多垂直行业领域,把Rel-15/16未能实现及完成的系统功能做得更全面、更精细,以更逼近“全频谱、全覆盖、全应用”万物互联的通信愿景,同时也为下一代6G蜂窝系统做好了铺垫和基线。基于3GPP Rel-17业界最新的立项动态信息,对潜在重要的系统特征功能进行了全面介绍、归类和整理,并从终端、网络、运营三大阵营维度进行了提炼分析,提出了各个阵营维度最为关注的标准研究点和未来价值利益倾向。依据梳理出的相关规律,希望相关研究者能够对蜂窝系统功能演进的趋势具有更深入的理解和判定。     

RedCap标准及产业进展

<正>3GPP于2022年6月冻结的5G标准版本Rel-17，面向中高速连接场景引入了第一项基于5G的蜂窝物联网技术，并定义为5G轻量化终端设备类型——“RedCap”。国内外同步启动RedCap技术研发，IMT-2020(5G)推进组基于产业发展节奏，分两个阶段规划我国RedCap技术试验，2022年已完成关键技术测试，2023年将开展设备端到端的互操作测试。     

TD—HSPA在国内的进展与应用状况

文章主要通过研究3GPP Rel-5及Rel-7版本中的HSDPA／HSUPA技术及其特色,从商用角度阐述了TD—HSPA的应用状况和演进前景,不仅分析了TD—HSPA在国内的进展和技术优势,而且论述了TD—HSPA（＋）／LTE TDD技术对于无线通信的促进作用。文章指出,随着移动互联网技术的发展,TD—HSPA将在整个无线通信领域扮演重要角色并发挥有效作用。     

5G移动性增强关键技术及应用分析

3GPP在Rel-15版本中,NR移动性管理只引入了基本的切换功能,而NR切换0 ms中断时延是为UE提供无缝切换感受的性能需求之一,且在高频移动时UE可能会遇到快速的信号恶化,切换的可靠性也会降低,如何减少切换过程中的数据中断时间以及提高移动鲁棒性是R16一个重要研究方向.针对以上问题,R16移动性增强提出了两个关键...     

GaN HEMT电力电子器件技术研究进展

GaN高电子迁移率晶体管(HEMT)器件由于其击穿场强高、导通电阻低等优越的性能,在高达650 V额定电压等级的高效、高频转换器中有着广泛的应用前景。GaN HEMT器件的特性优势与其工艺结构、材料特性密切相关。介绍了耗尽型、增强型GaN HEMT的典型器件结构,并将国内外对结构设计以及材料优化等关键技术问题的研究现状进行了综述,并概括总结了GaN HEMT的技术发展趋势和最新参数指标。     

Performance analysis and enhancement of random access process in cellular-IoT

Narrowband Internet of things (NB-IoT) and enhanced machine-type communications (eMTC) are two new IoT-oriented solutions introduced by the 3rd generation partnership project (3GPP) in Rel-13. In order to meet the new requirements (such as long battery life, low device cost, low deployment cost, extended coverage and support for a massive number of devices) of machine-to-machine (M2M) communication, these two technologies had some improvements on the random access (RA) mechanism compared to traditional long term evolution (LTE). For example, repetition of preamble transmission and coverage enhancement (CE) levels have been proposed to offer communication services in a wider area. In addition, NB-IoT has adopted a new spectrum allocation method and proposed a new type of preamble structure to meet the requirement of big amount of connections. We summarize details and differences of the RA process in LTE, eMTC and NB-IoT. Afterwards, as an improvement, we propose an enhanced access protocol for NB-IoT. Finally, performance analysis and comparison are presented in terms of access success probability, average access delay, access spectrum efficiency and average number of RA attempts.     

Mobility and Handover Management for Heterogeneous Networks in LTE-Advanced

3GPP Long Term Evolution-Advanced (LTE-A) aims at enhancement of LTE performance in many respects including the system capacity and network coverage. This enhancement can be accomplished by heterogeneous networks (HetNets) where additional micro-nodes that require lower transmission power are efficiently deployed. More careful management of mobility and handover (HO) might be required in HetNets compared to homogeneous networks where all nodes require the same transmission power. In this article, we provide a technical overview of mobility and HO management for HetNets in LTE-A. Moreover, we investigate the A3-event which requires a certain criterion to be met for HO. The criterion involves the reference symbol received power/quality of user equipment (UE), hysteresis margin, and a number of offset parameters based on proper HO timing, i.e., time-to-trigger (TTT). Optimum setting of these parameters are not trivial task, and has to be determined depending on UE speed, propagation environment, system load, deployed HetNets configuration, etc. Therefore, adaptive TTT values with given hysteresis margin for the lowest ping pong rate within 2 % of radio link failure rate depending on UE speed and deployed HetNets configuration are investigated in this article.     

Impacts of additive uniaxial strain on hole mobility in bulk Si and strained-Si p-MOSFETs

Hole mobility changes under uniaxial and combinational stress in different directions are characterized and analyzed by applying additive mechanical uniaxial stress to bulk Si and SiGe-virtual-substrate-induced strained-Si (s-Si) p-MOSFETs (metal-oxide-semiconductor field-effect transistors) along <110> and <100> channel directions. In bulk Si, a mobility enhancement peak is found under uniaxial compressive strain in the low vertical field. The combination of (100) direction uniaxial tensile strain and substrate-induced biaxial tensile strain provides a higher mobility relative to the (110) direction, opposite to the situation in bulk Si. But the combinational strain experiences a gain loss at high field, which means that uniaxial compressive strain may still be a better choice. The mobility enhancement of SiGe-induced strained p-MOSFETs along the (110) direction under additive uniaxial tension is explained by the competition between biaxial and shear stress.     

Mobility Enhancement Technology for Scaling of CMOS Devices: Overview and Status

The aggressive downscaling of complementary metal–oxide–semiconductor (CMOS) technology to the sub-21-nm technology node is facing great challenges. Innovative technologies such as metal gate/high-k dielectric integration, source/drain engineering, mobility enhancement technology, new device architectures, and enhanced quasiballistic transport channels serve as possible solutions for nanoscaled CMOS. Among them, mobility enhancement technology is one of the most promising solutions for improving device performance. Technologies such as global and process-induced strain technology, hybrid-orientation channels, and new high-mobility channels are thoroughly discussed from the perspective of technological innovation and achievement. Uniaxial strain is superior to biaxial strain in extending metal–oxide–semiconductor field-effect transistor (MOSFET) scaling for various reasons. Typical uniaxial technologies, such as embedded or raised SiGe or SiC source/drains, Ge pre-amorphization source/drain extension technology, the stress memorization technique (SMT), and tensile or comprehensive capping layers, stress liners, and contact etch-stop layers (CESLs) are discussed in detail. The initial integration of these technologies and the associated reliability issues are also addressed. The hybrid-orientation channel is challenging due to the complicated process flow and the generation of defects. Applying new high-mobility channels is an attractive method for increasing carrier mobility; however, it is also challenging due to the introduction of new material systems. New processes with new substrates either based on hybrid orientation or composed of group III–V semiconductors must be simplified, and costs should be reduced. Different mobility enhancement technologies will have to be combined to boost device performance, but they must be compatible with each other. The high mobility offered by mobility enhancement technologies makes these technologies promising and an active area of device research down to the 21-nm technology node and beyond.     

3GPP对异构网络移动性优化技术的研究进展

随着异构网络技术的快速发展,移动通信技术将迎来大的变革,3GPP也把对异构网络的相关研究和标准制定做为重点工作之一。本文介绍了3GPP在R11阶段对异构网络移动性能的研究和所提出的异频低功率小区探测优化技术。     

单轴附加应变对体硅及应变硅p-MOSFETs空穴迁移率的影响

Hole mobility changes under uniaxial and combinational stress in different directions are characterized and analyzed by applying additive mechanical uniaxial stress to bulk Si and SiGe-virtual-substrate-induced strained- Si（s-Si）p-MOSFETs（metal-oxide-semiconductor field-effect transistors）along 110 and 100 channel directions. In bulk Si,a mobility enhancement peak is found under uniaxial compressive strain in the low vertical field.The combination of 100 direction uniaxial tensile strain and substrate-induced biaxial tensile strain provides a higher mobility relative to the 110 direction,opposite to the situation in bulk Si.But the combinational strain experiences a gain loss at high field,which means that uniaxial compressive strain may still be a better choice.The mobility enhancement of SiGe-induced strained p-MOSFETs along the 110 direction under additive uniaxial tension is explained by the competition between biaxial and shear stress.