5G meets satellite: Non-terrestrial network architecture and 3GPP

With 3GPP Release-17, global 5G standards now support non-terrestrial mobile networks comprising radio access network, terminals, and core network. This enables multi-vendor interoperability as well as interoperability with 3GPP-compliant 5G systems. This paper describes the key features enabling the NG-RAN architecture defined for 5G to support non-terrestrial networks. Starting from a general overview of NG-RAN and of the new paradigms of NTN, we introduce the NTN functionality in NG-RAN specifications with respect to feeder link switchover, cell handling, terminal registration, and OAM aspects. We also discuss different scenarios combining satellite access with 3GPP-defined core networks. We also describe some further enhancements expected to be seen in the next 3GPP release (Rel-18). We believe current and upcoming 3GPP work for NTN represents a solid basis on which 5G satellite networks can be built in the upcoming future.     

Physical layer enhancements in 5G-NR for direct access via satellite systems

Among the several features and capabilities introduced by every new 3GPP release on 5G cellular systems, the latest Release 17 will be remembered as the first that specifies a set of enhancements and adaptations to support mobile broadband services via satellite direct access. Specifically focused on the necessary physical layer mechanism and procedure modifications, this paper will present in detail the 3GPP work about the inclusion of satellite systems in 5G networks.     

Network aspects of integrating 5G and satellite communication

Since 2017, 3rd Generation Partnership Program (3GPP) is working on integration of satellite communication in 3GPP. This paper discusses the results of the work on service and network architecture aspects in 3GPP Technical Specification Group (TSG) Service and System Aspects (SA) and 3GPP TSG Core Networks and Terminals (CT). This paper does not discuss radio aspects as are specified in 3GPP TSG radio access network (RAN). 3GPP first specified requirements and use cases for satellite access. Subsequently, architecture and protocol specifications were created for integration scenarios, direct access, network selection, mobility management, and satellite backhaul with quality of service (QoS). Also, impacts of regulatory aspects on satellite integration have been discussed in 3GPP. With the completion of Release 17, 3GPP specifications are now ready for implementation of integrated 5G satellite networks. 3GPP will continue with further development of satellite integration in Release 18 and Release 19.     

Latest progress on 3.5 GHz 5G NR trial

The 5^thgeneration mobile system (5G) was designed to fulfill the mobile market requirements for higher data rate,lower latency and higher connection density beyond 2020.3.5 GHz spectrum was a typical band for 5G deployment and could be a global band for 5G development.The performance of 3.5 GHz 5G would be very meaningful as a reference for global operators.Based on the first release of 5G specification frozen in June 2018 by 3^rdgeneration partner project (3GPP),field trials of 5G network in typical urban area were conducted to validate the peak data rate,cell throughput and latency of 5G network.The trial results show that 5G NR system can achieved 1 Gbit/s peak data rate and 4 ms latency of single direction.     

5G新空口设计:如何从LTE拓展与创新

在“万物互联”愿景的驱动下,国际电信联盟为5G提出了高速率、低时延、海量连接三大应用场景以及相关的性能指标需求。相应地,国际标准组织3GPP中完成了具体技术研究和标准化,形成了5G新空口的设计。首先,对于为何5G新空口设计可以重用LTE的基础设计进行了分析,亦即MIMO-OFDM的框架是如何满足国际电信联盟定义的三大需求的;其次,对5G新空口与LTE的重点差异进行了总结,包括新架构、新设计、新频段、新天线 “四新”的具体内容。最后对未来技术发展趋势做了简单的介绍。     

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0ms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技术—双活动协议栈和条件切换。详细阐述了两种关键的增强技术以及各网元之间的协作情况,研究了与传统切换流程的差异、UE侧的协议栈变化,分析了两种移动性增强技术的应用场景,给出了中信科移动预规划的应用方案,为移动性增强技术的研究和应用提供参考。     

NR覆盖增强方案及标准化进展

为提升5GNR网络的覆盖性能,研究并讨论覆盖瓶颈信道的相关覆盖增强方案,包括物理上行共享信道的重复传输增强、多时隙传输块处理、联合信道估计方案,物理上行控制信道的动态重复传输指示、解调参考信号绑定方案,以及随机接入中的Msg3信道的重复传输方案.基于上述增强方案,聚焦3GPP Release 17 NR覆盖增强的标准化...     

5G终端空闲态节能方案分析

由于大带宽、大规模天线、高速率等新特性的引入,5G终端的能耗问题比4G终端更加严峻,成为影响5G网络用户体验的重要原因之一。3GPP标准化组织开展了与NR终端节能课题相关的研究,R16协议版本主要面向连接态下的终端节能优化,R17协议版本则主要面向空闲态终端节能优化。首先分析了空闲态下的终端节能问题,同时与LTE终端能耗进行对比。针对寻呼检测和时频跟踪过程的能耗问题提出了节能优化解决方案,进行了节能增益分析,该方案可以降低5G终端的能耗,为后续5G商用终端空闲态的节能技术指明了方向。     

2.6 GHz下的5G NR覆盖能力分析

当前关于5G新空口的研究主要集中在中高频段,4G使用的低频段重耕对于5G规模连片组网意义重大,但对此研究较少。在讨论影响无线电传播能力因素的基础上,选取3GPP TR38.901中城区室外非视线传播模型,使用当前主流空口参数,进行多系统主要物理信道传播能力的仿真。通过对比4G和5G NR各频段相同物理信道的覆盖能力,得到2.6 GHz频段下的5G NR主要信道覆盖能力可在现有4G基础上实现连片覆盖。     

无人机高清直播5G无线部署方案分析

随着3GPP R16标准的冻结,5G与各垂直行业的融合将更加深入,无人机可在5G技术的支持下实现性能增强与应用领域拓广。无人机高清直播业务尚处于刚起步状态,业界暂未形成统一成熟的解决方案。通过直播业务需求进行研究分析,进而提出了三种针对该应用场景的无线侧部署方案,并根据现网测试数据对上下行速率、时延等关键指标进行了分析。     

卫星通信在5G非地面网络架构中的应用和问题分析

本文介绍了5G非地面网络（Non-Terrestrial Networks /NTN）的应用场景，对比分析了采用卫星通信实现5G NTN的不同网络架构及其适合的应用方式，并进一步探讨了5G NTN急需解决的问题，提出可行的解决思路。     

Introduction to the 3GPP-defined NTN standard: A comprehensive view on the 3GPP work on NTN

With the recent publication of a set of technical specifications in 3rd Generation Partnership Project (3GPP) related to non-terrestrial network (NTN) enhancements, a global standard for satellite systems is newly defined aiming to support any orbit, any frequency band, and any device. It opens the door for the seamless integration of satellite network component in 5G system and beyond, delivering the promise of a ubiquitous mobile system that can support new use cases. The emergence of hybrid terrestrial-satellite systems is the result of a joint effort between stakeholders of both mobile and satellite industries and is paving the way to new business opportunities. This paper attempts to provide a comprehensive view on this 3GPP NTN standard and what are the next steps.     

Radio interface protocols and radio resource management procedures for 5G new radio non-terrestrial networks

In Release 17, 3GPP introduced adaptations and enhancements to the 5G new radio (NR) specification to support non-terrestrial networks (NTNs) operation. The main challenges were due to long propagation delays, especially in GEO deployments, and the movement of the satellites in LEO deployments. In this paper, we give an overview of the protocol adaptations to support NTNs. The main user plane protocol adaptations include changes to random access and hybrid automatic repeat request to due long propagation delays. The control plane protocol adaptations include a variety of mobility related enhancements for user equipment.     

5G非授权频段接入关键技术及国际标准化

非授权频谱作为5G授权频谱的补充可以满足运营商及垂直行业的多种应用,3GPP在R16阶段对5G NR在非授权频段的接入进行了研究和标准化。结合非授权频段的监管规则,对5GNR在非授权频段的关键技术及国际标准化内容进行了详细的分析。具体包括5G在非授权频段的帧结构设计增强、物理信道设计增强、物理过程设计增强。基于这些技术分析,本文对非授权频谱使用5G技术进行了总结和展望。     

5G广播电视演进和主要技术特点

地面无线广播电视作为广播电视最为重要的传输手段,在广播电视发展的很长一段时间内占据主导地位。随着计算机、微电子、移动通信、材料科学等技术飞速发展和人们不断提高的精神、物质、文化需求,无线广播电视技术开始探索向移动终端和个性化领域发展,广播电视与通信技术的融合已经成为全球性话题和探索研究方向。以国际通信组织3GPP为代表的通信与广播电视技术人员,从本世纪初开始了对现代广播电视传播体系的全面系统研究和探讨。本文全面介绍了3GPP广播模式的发展历程和主要技术特点,并基于我国广电兼具广播运营商和电信运营商的双重身份,指出了广电5G广播电视网建设演进路线,建议了未来中国3GPP广播电视分三阶段发展,提出了中国广播电视的核心模式:卫星组网+地面广播+基站覆盖。     

一种5G NR系统PSS叠加分段的定时同步算法

对于第三代合作伙伴计划(The 3rd Generation Partnership Project,3GPP)中的5G新空口(New Radio,NR)系统,同步信号检测算法的计算非常复杂,根据主同步信号的特性,提出了分段互相关与对应叠加的联合检测算法。该算法只对接收信号进行一次与本地主同步信号(Primary Synchronization Signal,PSS)序列之和的分段相关处理,即可得到相关峰值的位置,并检测到粗同步点的位置,进一步对粗同步点做局部互相关,根据最大峰值检测出精同步点,降低了计算的复杂度。对传统互相关算法、分段互相关算法和改进算法进行了理论推导和复杂度对比分析,结果表明,相对于传统互相关算法,改进后的算法有效降低了计算量,提升了抗频偏性能。     

LTE空中接口在卫星通信中的适用性

目前LTE体制已成熟,在卫星通信系统中应用LTE技术有利于星地一体化网络的发展.移动卫星系统在4G网络中成功应用的一个关键因素是设备和地面系统得到最大的通用性.一种有效的解决这个问题的方法是利用地面空中接口作为卫星空中接口的基础.由于3GPP(The 3rd Generation Partnership Project...     

HSDPA接口新特性及TCP和UE容量分析

为满足日益增长的高速互联网连接和网络多媒体服务的需求,3GPP W-CDMAR5版本中引入高速下行分组接入HSDPA（High Speed Downlink Paekct Access）技术,W-CDMA;引入HSDPA技术可以提供高速率的数据连接和更大的用户容量．并且向下兼容R99版本本文详细介绍丁HSDPA新的接口类型和特性．并基于TCP和UE容量两个方面对HSDPA系统新特性进行了分析。     

5G NR性能需求和物理层设计要点

文章首先介绍了5G的四大场景,即连续广域覆盖、热点高容量、低功耗大连接和低时延高可靠;然后提供了5G NR物理层基本参数以及NR物理层参数与LTE物理层参数的对比;最后给出了5G NR物理层的设计要点,包括更大的频率范围、更大且更为灵活的信道带宽、多种信道栅格、同步栅格、灵活的子载波间隔、灵活的帧结构、自适应BWP以及在数据信道、控制信道、参考信号、PRACH和波束管理方面的改进。     

Research on nanosecond time synchronization technology for 5G base station based on GNSS neighborhood similarity

For precision positioning requirements in the LTE-A/5G service developed by the 3GPP,the nanosecond precision time synchronization technology based on global navigation satellite system (GNSS) for 5G base station was studied which broke through the current GNSS receiver’s hundred nanosecond timing accuracy.By analyzing the characteristics of neighborhood similarity of GNSS errors and combining the characteristics of time synchronization requirements of 5G base stations,a nanosecond precision time synchronization theory and related receiver algorithms for 5G base stations was proposed which based on the principle of neighborhood similarity of GNSS signals.The specific characteristics of the time synchronization technology under regional and wide-area conditions were studied.The simulation and experimental results show that compared with the current time synchronization accuracy within hundred nanosecond rang of base stations,the proposed method can achieve precision time synchronization within 3 ns between the regional base stations,and support 5G base station meter-level precision location based service(LBS) and other advanced incremental services.