LTE-Advanced载波聚合技术与标准进展

LTE-Advanced是基于LTE的增强与演进,载波聚合技术是LTE-Advanced的关键技术之一。文章介绍了LTE-Advanced载波聚合技术的背景、技术构成及在3GPP中的标准化进程,并总结了该技术的下一步研究重点与发展方向。     

第四代移动通信关键技术研究

介绍了第四代移动通信技术——LTE-Advanced(包括TD-LTE-Advanced及LTE-Advanced FDD)产生的背景,重点阐述了LTE-Advanced系统中载波聚合技术、增强MIMO(Multi-input Multi-output多输入多输出)天线技术、中继技术、异构网络等关键技术的特点及相应的研究内容。     

载波聚合技术对LTE-Advanced空口协议带来的挑战

载波聚合技术是LTE-Advanced标准的一个重要特性,也是实现LTE-Advanced系统百兆带宽运行的最关键技术,但其也对LTE-Advanced空口协议带来了诸多挑战。为了支持载波聚合技术,LTE-Advanced需要对此前的LTE空口协议进行多方面的增强。本文从成员载波分类、上行时钟提前、系统信息处理、无线链路失败处理等方面介绍了目前3GPP正在讨论的针对载波聚合的空口协议增强方案,包括已经形成的结论以及后续还需研究的问题。     

LTE-Advanced标准进展及演进策略分析

LTE-Advanced作为4G的候选技术方案,是在LTE基础上的进一步增强。本文对3GPP LTE-Advanced中各关键技术标准化的进展及热点问题进行讨论,并且对3G移动通信技术向LTE/LTE-Advanced未来移动通信技术的演进策略进行分析。     

LTE-Advanced MIMO增强技术研究

针对LTE-Advanced中的5个关键技术,选择MIMO增强技术进行深入研究和阐述。从技术原理、算法实现、测试验证、网络兼容性多个维度讨论了LTE-Advanced下行传输模式9(TM9),分析了TM9的使用范围、性能优势和兼容性问题;并在此基础上,横向对比了LTE和LTE-Advanced的所有天线模式,给出布网建议。     

LTE-Advanced关键技术及标准化进展

LTE-Advanced作为4G的候选技术方案,是在LTE基础上的进一步增强。本文介绍了3GPP中LTE-Advanced的各个关键技术及其标准化情况,包括载波聚合、多点协作传输、上下行MIMO传输以及中继等。     

LTE-Advanced关键技术演进趋势

文章对LTE-Advanced的定位及需求进行了分析,对LTE-Advanced技术和网络演进趋势进行了研究,指出LTE-Advanced的重点工作方向将放在RRM技术和网络架构优化方面。     

LTE-A中自适应多流波束赋形算法研究

多流波束赋形技术是LTE-Advanced中采用的多天线增强技术。采用单用户多流波束赋形技术,可以使得单个用户在某一时刻可以进行多个数据流传输,在提升系统性能上表现出极大优势。提出一种LTE-Advanced中下行单用户自适应多流波束赋形算法,基站端基于接收模型对下行链路容量进行预估计,在一定信噪比要求的条件下,以信道容量最大化准则选择波束赋形流数。仿真结果表明,自适应算法增加了波束赋形系统的灵活性,能够有效提高LTE-Advanced系统中下行链路性能。     

LTE/LTE-Advanced R10标准化进展

介绍了LTE/LTE-Advanced标准发展概况,详细分析了近期LTE-Advanced R10版本技术标准化情况及可行性阶段技术的进展,同时展望了LTE-Advanced R11版本的发展方向,最后分析了TD-LTE现网测试情况。     

LTE-Advanced标准化进展

作为ITU于2010年10月通过的4G标准之一,LTE-Advanced是3GPP长期演进(LTE)标准的增强版。文章给出了3GPP LTE-Advanced标准化时间表和关键性能,说明了载波聚合的工作原理,介绍了下行链路和上行链路多天线增强方案,描述了异构网络部署场景,验证了中继对LTE-Advanced网络性能的改善功能,最后预测了LTE-Advanced R11标准化发展趋势。     

VLIW DSP for mobile applications

We have developed a new digital signal processor (DSP) core for handheld terminals, the SPXK5 performance and flexibility, is compatible with high-level languages, and its architecture features low-power consumption. We describe the SPXK5 architecture and its performance in DSP applications. We also consider the question of application-specific enhancements. Such architecture enhancements as add-compare-select instructions or coprocessors for the Viterbi (1995) decoding algorithm are employed in some programmable DSPs, and for video codecs, other architectures include either single-instruction multiple-data (SIMD) instructions or media coprocessors. While such application-specific enhancements are valuable when their applications are actually in use, they do nothing to enhance the performance of other applications, and the more they are added, the greater the increase in chip size and energy requirements. In other words, for handheld terminals, such enhancements need to be chosen in a careful and balanced way. We have done this in developing the SPXK5, in which a wide range of signal processing algorithms are efficiently implemented     

HDR and image abstraction framework for dirt free line drawing to convey the shapes from blatant range images

Multidimensional Systems and Signal Processing - Due to the evolution of computer vision and non-photorealistic rendering (NPR) techniques, enhancements of image features from blatant range images...     

The CBX II Switching Architecture

This paper describes the architecture of the ROLM CBX II, a highly modular successor to the ROLM CBX. The paper outlines the physical and logical construction of the system and its capabilities, concentrating on data communications. The development goals for the system are presented, and the system characteristics are related to the goals. Architectural features which provide the basis for future enhancements are described.     

NASA's advanced tracking and data relay satellite system for theyears 2000 and beyond

An advanced tracking and data relay satellite system (ATDRSS) reference architecture that embodies many of the system features and technological enhancements considered essential is presented and described. The architectural and user service features of the existing TDRSS are reviewed, and certain evolutionary features that will take place by the mid-1990s are discussed. NASA's projected user service requirements for the first decade at the next century, which are the principal drivers for the ATDRSS architecture, are described, including such aspects as the real-time data rates and the quantity of simultaneous services that must be supported. The discussion of the ATDRSS reference architecture covers rationale, technology considerations, and key features of the future ATDRSS user service. A status summary of the ATDRSS program is given     

3GPP R12标准进展分析

3GPP R12于2012年9月开始正式进行标准化。作为应对未来无线通信业务指数级增长的关键环节,R12将是LTE版本中具有重要意义的一个大版本演进。本文主要针对R12中的一些重要技术项目和特点进行了阐述和分析。首先对3GPP组织架构及版本管理进行了相关介绍。然后就3GPP R12的重要特征进行了阐述分析,其中小小区增强(Small Cell Enhancements)成为R12中最重点的项目;立项众多,会上占用时间成为能否成功立项的依据;增强型和延续性项目为主;中国公司影响力上升。     

Design and performance evaluation of LTP enhancements for lossy space channels

This paper deals with the performance of Licklider Transmission Protocol (LTP) in space environment, focusing on the impact of segment losses and the design of possible improvements. The in‐depth analysis of retransmission mechanisms carried out in the paper shows that, while LTP already achieves delivery time performance very close to the theoretical optimum in ideal conditions (no losses) and when losses affect data segments, a substantial improvement is still possible concerning signaling segments, whose loss can result in a significant increase of the LTP block delivery time. To this end, 2 simple enhancements, the Closing State and the proactive retransmission of signaling segments, are proposed and evaluated in the paper. Both enhancements have been added as optional features to the original Interplanetary Overlay Network LTP implementation (ION 3.5.0), in order to evaluate their effectiveness on a GNU/Linux testbed running the full protocol stack. Results presented in the paper confirm the validity of the proposed enhancements, as they significantly reduce the average delivery time in the presence of high losses and provide the additional advantage, even when losses are relatively low, of largely reducing the difference between average and worst cases.     

VXIbus Revision 2.0-what's new?

The VXIbus Consortium recently finished work on a couple of new specifications. VXI-1, Revision 2.0 is the latest version of the VXIbus System Specification. It combines several forward-looking enhancements with other new features that improve interoperability, while maintaining full backward compatibility. The new VXI-8, Cooling Characterization Methodology Specification, is the culmination of several years of work to define a repeatable method for specifying and measuring the cooling capability of VXIbus mainframes     

Recent advances in dielectric-resonator antenna technology

This paper features some of the advances in dielectric-resonator antenna technology at the Communications Research Centre. Several novel elements are presented that offer significant enhancements to parameters such as impedance bandwidth, circular-polarization bandwidth, gain, or coupling to various feed structures. Several linear and planar arrays are also presented, to illustrate the performance of dielectric-resonator antenna elements in the array environment     

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.     

Wireless Security

This paper describes the security features incorporated into the third generation (3G) mobile system developed in 3GPP, specifically the enhancements to the shared secret symmetric authentication scheme as used in GSM. The proposed security architecture for the Internet multimedia subsystem (IMS) based on and built upon Internet applications, services and protocols, is then described. Finally, the paper describes some early work by 3GPP to integrate public key security mechanisms into 3G, while maintaining the global reach and call set-up performance, that mobile users now take for granted.