频带聚合技术在LTE-Advanced系统中的应用

为了满足无线网络日益增长的数据业务的需求,LTE-Advanced系统引入了频带聚合技术增加单个用户的传输带宽。在保持对现有协议修改不大和对LTE终端良好兼容性的前提下,频带聚合技术能够大幅度提高LTE-Advanced终端的峰值速率。文章介绍了频带聚合的原理和主要技术方案,讨论了使用频带聚合对系统控制信道设计、切换和频谱效率的影响。     

LTE-Advanced中的载波聚合技术研究

随着移动通信技术的发展,用户对数据速率的要求越来越高,与此同时频谱资源紧缺的问题日益严重。为了满足LTE-A系统对带宽的需求而提出了频谱聚合技术。与LTE系统相比,LTE-A系统需要在上下行控制信道设计、功率控制、TDD特定场景等多方面做相应的改变以支持频谱聚合的功能。     

Optimal rate and power allocation under quality‐of‐service requirements for wireless multihop networks

In wireless networks, real‐time applications have strict QoS requirements for packet delay, packet loss, and reliability. However, most existing work has not considered these QoS metrics when allocating wireless resources so that the QoS requirements of real‐time applications may not be satisfied. To overcome this shortcoming, a rate and power allocation framework incorporating these QoS metrics is first proposed for slow‐fading systems. Second, two distributed algorithms are developed to solve this optimization framework although it is nonconvex and nonseparable. Third, an improved framework is proposed to deal with the rate and power allocation with QoS requirements for fast‐fading systems. It is shown that the fast‐fading state of the network does not need to be considered in this improved framework, and it can be solved using algorithms that are similar to those for the framework of slow‐fading systems. In the end, simulations show that our algorithms converge closely to the globally optimal solution. By comparison with an existing model, simulations also verify the validity of our frameworks on dealing with the rate and power allocation with QoS requirements. Copyright © 2012 John Wiley & Sons, Ltd.     

LTE-A载波聚合调度方案研究与改进

基于LTE-Advanced系统中的载波聚合技术,对现有的3种资源调度机制:联合用户调度方案(Joint User Scheduling, JUS)、独立随机用户调度方案(Separated Random User Scheduling,SRUS)和独立数据突发级调度方案(Separated Burst Level Scheduling, SBLS)进行研究。针对3种机制在系统吞吐量、排队时延和成分载波(Component Carrier,CC)切换时延性能上的优缺点,提出了半独立负载调度机制(Half Separated Load Scheduling,HSLS)。HSLS采用动态负载均衡准则(Dynamic Load Balance,DLB),另外HSLS基于系统吞吐量和排队时延的要求以多数据突发(multi-burst)作为资源分配粒度,令多个调度器(Resource Scheduler, RS)可以同时分发满足调度条件的用户数据。仿真结果表明,HSLS对设备要求度低,有着良好的系统吞吐量和时延性能表现。     

载波聚合技术在4G+网络中的应用研究

针对4G用户的快速增长以及4G网络规模的持续扩大,2016年国内三大运营商将大规模升级LTE网络至4G+,即在原有4G网络的基础上利用载波聚合技术.介绍了载波聚合技术的背景及功能,对载波聚合技术的频谱聚合方式、载波管理以及载波聚合部署方案进行了简要介绍.结合国内运营商现有频谱资源,探讨了国内三大运营商载波聚合频谱组合方式,最后针对中国联通的现有频谱资源,给出了中国联通载波聚合部署的方案建议,为即将升级的4G+网络建设提供一些参考.     

On centralized schedulers for 802.11e WLANs distribution versus grouping of resources allocation

Wireless LAN is becoming a pervasive wireless access technology that can be found in almost any mobile device such as laptops, PDAs, portable game consoles and mobile phones. Each of these groups of devices have a different set of requirements according to their intended use and applications but most of them share two main requirements: QoS support to satisfy applications' demands and power saving functionality to achieve an operating time according to users' expectations. IEEE 802.11e defines two centralized solutions in order to address these problems: Hybrid Coordination Channel Access (HCCA) for QoS and Scheduled Automatic Power Save Delivery (S‐APSD) for power saving. The focus of our work in this paper is the analysis and evaluation of a proposed centralized scheduler that makes use of both aforementioned IEEE 802.11e QoS and power saving solutions. Our contributions are as follows: (i) Design and analytical modeling of a proposed centralized scheduler (DRA) that maximizes the minimum distance between the resource allocations with pseudo‐polynomial complexity, (ii) Extensive performance evaluation of the QoS and power saving benefits of the Distribution proposal (DRA) as compared to a generic Grouping one (GRA), and (iii) Evaluation of the complexity and scalability of the proposal to assess its feasibility in practice. Copyright © 2010 John Wiley & Sons, Ltd.     

Power control for delay constrained multi‐channel communications using outdated CSI

In this paper, we study the power allocation scheme for a single user, multi‐channel system, e.g., orthogonal frequency‐division multiplexing (OFDM) systems, under time‐variant wireless fading channels. We assume the receiver feeds back perfectly estimated channel state information (CSI) to the transmitter after a processing delay. The objective of the power allocation is to maximize throughput subject to quality‐of‐service (QoS) constraint. The QoS measure of our consideration is a triplet of data rate, delay, and delay bound violation probability. A two‐step sub‐optimal power allocation scheme is proposed to address the impact of outdated CSI. In the first step, the total transmission power that can be used within one block is determined according to the summation of the channel gains of all the channels. In the second step, the total transmission power is allocated among all the channels. The proposed power control scheme is less sensitive to the feedback delay. Compared to the optimal power allocation scheme designed for the perfect CSI scenario, it has lower computational complexity while achieving comparable capacity. Copyright © 2010 John Wiley & Sons, Ltd.     

LTE-Advanced系统与S-band雷达共享频谱的载波聚合资源分配

频谱共享可以缓解频谱资源有限以及已分配的频谱资源利用率非常低的压力,而且载波聚合技术可以应用于频谱共享场景中。针对以上问题,首先,提出一个具体的MIMO雷达与LTE-Advanced蜂窝系统之间的频谱共享场景,利用载波聚合技术实现两载波聚合;其次,由于不同的用户设备运行的应用程序不尽相同导致其所需带宽也不尽相同,于是,提出基于用户应用类型的资源分配最优算法,给予实时应用用户优先权;最后,通过MATLAB仿真平台对此算法的性能进行仿真和验证。仿真结果表明,载波聚合可以提供更大的带宽从而提高用户设备的数据传输速率,资源分配最优算法可以保证用户的最小服务质量。     

城市电网中电力线载波通信的频谱分配与管理

随着智能电网和物联网技术的快速发展,电力线载波通信（PLC）作为一种高效的数据传输技术,降低了通信成本。文中介绍了PLC技术的工作原理,探讨了PLC的通信模式,分析了国际频谱分配标准、国家频谱分配政策以及城市电网特定需求分析,强调了PLC频谱使用需遵守的相关规则。深入分析PLC技术的工作原理和通信模式,可以为PLC 系统的设计和应用提供技术指导。     

存在反馈延迟时V-BLAST系统的功率分配算法

针对信道反馈有延迟条件下的垂直贝尔实验室分层空时(Vertical Bell Laboratories Layered Space Time,V-BLAST)系统,提出基于最小均方误差检测(Minimize Mean Square Error,MMSE)的自适应功率分配算法.通过系统建模和性能分析,推导出系统瞬时信干噪比的条件概率密度函数,并得到V-BLAST系统的平均BER表达式.发 送端在总功率约束条件下,以瞬时BER为优化目标,利用拉格朗日极值法求解自适应功率分配矩阵.仿真结果表明,在信道反馈有延迟时,与等功率分配相比,采用所提算法可显著改善系统的BER性能.     

感知/传输帧结构下基于有效容量的多功率分配策略

传统认知无线网络功率分配时,一般假定主用户（Primary User,PU)状态在一帧内不发生变化,并且未考虑传输时延的问题。在下一代移动网络中,由于主用户活跃程度的提高以及严格的时延要求,上述问题是功率资源分配时亟需考虑的重要方面。针对这种问题,以最大化认知用户可获得的有效容量为目标,采用基于感知/传输帧结构的四状态三功率传输策略,从而满足时延约束要求,且考虑了主用户的活跃程度。建立了系统以及状态转移模型,设计了使用服务质量(Quality of Service,QoS)约束的平均信道有效容量优化函数,采用Lagrangian方法详细分析推导了最佳有效容量的理论近似值,并对影响有效容量的不同因素进行了仿真分析。与传统的传输策略相比,在保证主用户正常通信的前提下,采用所提算法,认知用户的有效容量得到了显著提高。     

QoS‐driven jointly optimal subcarrier pairing and power allocation for OFDM amplify‐and‐forward relay systems

In this paper, we investigate the quality‐of‐service (QoS) driven subcarrier pairing and power allocation for two‐hop amplify‐and‐forward OFDM relay systems. By integrating the concept of effective capacity, our goal is to maximize the system throughput subject to a given delay QoS constraint. We propose a jointly optimal subcarrier pairing and power allocation scheme, which can be implemented with two separate steps. First, pair the subcarriers over the source‐relay channel and relay‐destination channel by the descending order of the subcarriers’ channel gains. Second, by making use of the derived equivalent end‐to‐end channel gains of the subcarrier pairs, optimally allocate power over the subcarrier pairs, and then optimally partition the power of the subcarrier pairs between the source and the relay. The simulation results show that our proposed scheme can efficiently provide different levels of delay QoS guarantees, even if under stringent delay QoS constraints. The simulation results also verify that our proposed scheme shows significant superiorities over the other existing schemes. Copyright © 2013 John Wiley & Sons, Ltd.     

精品IP综合承载网构建思路探讨

分析了当前运营商在实际经营过程中面临的问题,结合运营商的业务及组网情况,从部署智能QoS策略、提升承载网可靠性及安全性、强化性能监测等角度,提出了构建精品IP综合承载网的思路。     

Delay analysis of DRX in LTE-advanced considering carrier aggregation

The long term evolution advanced (LTE-advanced) standards target at high system performance comparable or superior to the requirements of the International mobile telecommunications advanced (IMT-advanced). In order to support backward compatibility with LTE, most of the key technologies have been retained in LTE-advanced, one of which is the discontinuous reception mechanism (DRX). LTE-advanced adopts carrier aggregation technology to extend the system bandwidth, which requires the LTE DRX applied in single-transceiver scenario to be adapted to multi-transceiver scenario with multiple component carriers. Apparently, carrier aggregation will influence the performance of DRX severely, so it’s worth studying the impact brought by the coexistence of LTE DRX and carrier aggregation on the system performance, e.g., the system delay. In this paper, first an overview of DRX in carrier aggregation scenario is given. Then it is modeled as a Markov process based on the queuing theory. Simulation results show that the independent component carrier configuration with a uniform Inactivity Timer achieves a superior service delay performance compared with other reference schemes.     

LTE-A载波聚合技术的最新研究进展

为了满足国际电信联盟无线通信组(ITU-R,International Telecommunications Union-Radio Communications Sector)对4G峰值速率及最大带宽的要求,LTE-A系统引入新的候选技术——载波聚合(CA,Carrier Aggregation)。阐述了载波聚合中的主要关键技术,介绍了在新的标准制定过程中各项技术的进展和仍然存在的问题,并探讨了在3GPP TSG RAN WG1(第三代合作伙伴计划-技术研究小组-无线接入网工作组)第66/66b次会议中所提出的相关问题的最新解决方案,最后总结了载波聚合技术下一步的研究和发展方向。     

载波聚合技术在卫星移动通信中的适应性初步研究

本文对载波聚合技术在卫星移动通信中的适应性进行了初步讨论,根据不同频段的传输特性,讨论了卫星移动通信载波聚合传输参数的选取方法,给出了一种适合卫星移动通信的载波聚合数据分配方法,通过数值计算和分析,验证了本文所述方法的合理性和有效性。     

电信级以太网技术讲座第1讲电信级以太网的概念与关键特征

本文从基本概念入手,对于电信级以太网业务和技术的内涵与外延进行了分析,并总结归纳了电信级以太网技术的关键特征。     

基于柔性QoS的资源动态分配策略研究

本文在对QoS的柔性,描述和评价方法进行研究的基础上,针对频率资源有限的无线ATM网,提出了利用QoS的柔性在业务过程中对频率资源进行动态分配的方案和算法,并进行了实验仿真,结果表明利用QoS的柔性动态分配频率资源可以提高资源的利用率。     

支持QoS的多链路最少变换动态带宽分配算法

提出一种支持QoS的多链路最少变换动态带宽分配方法（MCDBA）,该方法实现了支持不同的QoS等级,量化了带宽分配的大小,在满足一定QoS限制的条件下最小化带宽分配变换次数。仿真结果验证了MCDBA能有效地减少数据分组的时延和提高系统的带宽利用率,MCDBA可用于解决大规模网络链路接入的复杂QoS控制的实际问题。     

电信级以太网技术讲座 第1讲 电信级以太网的概念与关键特征

本文从基本概念入手,对于电信级以太网业务和技术的内涵与外延进行了分析,并总结归纳了电信级以太网技术的关键特征。