TD-SCDMA基带拉远设备组网应用

首先对比TD-SCDMA系统中射频拉远、中频拉远和基带拉远三种技术,并对BBU与RRU之间的Ir接口技术要求进行了详细阐述;接着重点论述了基带拉远设备的应用场景、组网方式、Ir接口光纤连接方式和组网局限性.     

光纤射频拉远技术的应用研究

从光纤射频拉远设备的组网方式、设备原理、技术性能和实际组网应注意的事项等方面入手,深入介绍了光纤射频拉远技术将在3G网络建设和维护中得到的广泛应用。     

一种具备环网治愈功能的LTE数字基带射频拉远组网架构设计与研究

文章分析了目前数字基带射频拉远组网方式优势与弊端,提出了基于粗波分复用(CWDM)技术的LTE数字基带射频拉远环形组网架构,分析并给出了其组网架构的优越性。     

基带射频拉远站与传统宏基站在CAPEX和OPEX方面的比对分析

为了进一步了解TD-SCDMA基带射频拉远站的应用优势,从CAPEX和OPEX两方面出发,在单站建设、多站组网、维护成本等多个纬度对比了基带射频拉远站和传统型宏基站的投资和成本。     

射频拉远单元RRU与数字光纤直放站分析比较

文章首先对射频拉远单元RRU及数字光纤直放站工作原理、接口类型、组网方式分别进行了介绍，并就射频拉远单元RRU和数字光纤直放站进行了详细的分析和比较。     

基于光学相干调制技术实现基站载波光纤拉远的无线移动接入网络研究与设计

分析了目前数字基带射频拉远组网架构的优势与弊端,提出了基于光学相干调制技术实现基站载波光纤拉远的无线移动接入网络架构,分析了其组网架构的优越性,给出了该接入网的具体实施方式。     

TD—SCDMA系统室外单元拉远技术

介绍了当前系统中采用的三种室外拉远技术：射频拉远、中频拉远、基带拉远．分析了当前室外拉远技术在国内的发展趋势。同时结合它们各自在技术上的成熟度以及在组网上的优劣势,探讨了在目前TD—SCDMA系统建网中如何结合使用三种拉远技术．使其各自能发挥优势,使整个网络具有良好性能,并能在组网成本上更具有竞争力。     

TD—SCDMA系统室外单元拉远技术

本文介绍了当前系统中所采用的三种室外拉远技术：射频拉远、中频拉远．基带拉远,并分析了当前室外拉远技术在国内的发展趋势。同时结合它们各自在技术上的成熟度以及在组网上的优劣势,探讨了在目前TD—SCDMA系统建网中如何结合使用三种拉远技术．使其各自能够发挥优势来达到整个网络的良好性能,并能在组网成本上更具有竞争力。     

阿尔卡特朗讯WCDMA射频拉远解决方案

介绍了射频拉远技术的特点以及阿尔卡特朗讯针对不同应用情况的射频拉远解决方案。分析了采用射频拉远技术给运营商带来的好处，介绍了阿尔卡特朗讯射频拉远解决方案全球应用案例。     

3G数字基站射频拉远CPRI规范的实现

射频拉远技术可以为运营商降低成本并提高组网效率,基带处理和射频拉远两部分设备之间的标准化接口是有效实现控制与数据传输的保证。文章介绍了标准化接口之一的公共无线接口(CPRI)规范,讨论了基于软件和硬件上的设计。     

Reconfigurable remote radio head design and implementation for super base station applications

This paper proposes a reconfigurable remote radio head (RRH) software and hardware architecture and presents the results of its implementation. The implemented RRH has been designed for a centralized architecture super base station that facilitates the integration of 2G, 3G, and 4G ground base stations and geosynchronous equatorial orbit (GEO) satellite gateway stations. The reconfigurable RRH is a primary aspect of the system. By modifying the programmable software configuration from the perspective of software-defined radio, the RRH can support multiple frequency allocations. The RRH is composed of radio frequency (RF) modules, intermediate frequency (IF) modules, and some of the physical layer functions. The development of a reconfigurable IF module is emphasized. A filter-bank multiplexing technique has been employed for the IF module, which reduces the use of hardware resources. To this end, we experimentally evaluated the main key performance indicators (KPIs) of the RRH. The experimental results demonstrate that the proposed design attains the goal of reducing hardware costs and improving system flexibility and stability.     

Adaptive Energy Detection Based Solution for Fronthaul Problem in C-RAN

It hasbeen anticipated that the fifth generation (5G) wireless systems will deliver an efficient growth of the energy and spectral efficiency. To accomplish these goals, centralized radio access networks (C-RAN) is presented as the advanced wireless access networks paradigm with centralized baseband units (BBUs) and remote radio heads (RRHs). Although it is affected by Common Public Radio Interface (CPRI) limitations which requires high bandwidth for existing BBU/RRH interfaces. Moreover, the fronthaul links the BBU and RRH. But CPRI limits the deployment of C-RAN for fronthaul networking due to its fixed-rate fronthaul interface which transmit CPRI streams even in the absence of traffic load. However, this causes data transmission inefficient. So, the classical fronthauling method demands high bandwidth and the failure of fronthaul will cause losing a very high bandwidth. The purpose of this paper is to develop energy detection (ED) based algorithm which permits the secondary users to use the channel without interfering the primary users, so that the bandwidth in the fronthaul can be used in an efficient manner. A dynamic threshold with noise uncertainty based ED algorithm is proposed in this paper. It compares the fixed threshold with dynamic threshold by comparing probability of detection with probability of false alarm. Finally, by using this proposed algorithm, it can be concluded that performance of the probability of detection improves even with the presence of noise uncertainty.     

CLB: a multilevel co-operative load balancing algorithm for C-RAN architecture

The Fifth-Generation (5G) cellular and wireless communication envisage to integrate multiple technologies to provide a wide range of applications. The rapid growth of Information and Communication Technology (ICT) needs a common cellular platform to increase the network’s extensibility and adaptability. The Cloud Radio Access Network (C-RAN) offers a scalable and flexible Base Station (BS) architecture for the next-generation wireless and mobile networks, where the BS functionality is split into a distributed radio unit known as Remote Radio Head (RRH) and a Centralized BaseBand Unit (C-BBU). To further make the C-BBU scalable and flexible, the baseband signal processing is carried out over a virtualized platform. The load at the RRH and C-BBU can vary from under-loaded to overloaded conditions which increase the power consumption and degrade the Quality-of-Service (QoS) of the C-RAN. In this paper, we formulate under-loaded and overloaded conditions at the RRH and the C-BBU, and propose a Co-operative Load Balancing (CLB) algorithm for handling the cellular traffic in real-time under different load conditions. The proposed CLB aims to maximize the utilization of hardware resources at the RRH and C-BBU. The CLB algorithm is compared with CDI, CZ, NDLB, DLB in the first phase for the RF load balancing. In the second phase of simulation, CLB is compared with the FCFS, IWRR, OLB, GP and TLB algorithms for server (C-BBU) load balancing. The parameters considered for comparison are: User Entity (UE) waiting time, blocking probability and processing time at the RRH and the C-BBU. Simulation results show that the use of co-operative load balancing technique improves the QoS in the C-RAN by reducing the blocking probability and UE waiting time. The CLB algorithm is validated with LTE TU-Vienna and cloudSim simulators for the RRH and the C-BBU, respectively.     

阿尔卡特朗讯WCDMA射频拉远解决方案

针对WCDMA介绍了射频拉远技术的基本概念,并从集成度、网络建设和维护等方面介绍了射频拉远的特点,最后简单说明全球应用案例。     

Beamforming for heterogeneous cloud radio access network

To overcome the problem that previous researches for heterogeneous cloud radio access network (H-CRAN) mainly focus on single macro cell,and only considered the intracell interference in the one macro cell,while the inter cell interferences among different macro cells are neglected,H-CRAN with multiple macro-cells was studied,and the objective was to maximize system sum-rate through jointly optimizing the beamforming vectors of macro base stations (MBS) and remote radio heads (RRH).Based on alternating optimization and Lagrangian dual method,a joint MBS and RRH beamforming algorithm was proposed.The original problem was first divided into two subproblems.Then,the two sub-problem were solved alternately to obtain the final solutions of the original problem.In addition,the closed expression solutions of the two sub-problem were derived based on Lagrangian dual method.The proposed algorithm was compared with some beamforming algorithms in the simulation.The experimental results demonstrate the proposed algorithm has a better performance in improving the sum-rate of H-CRAN.     

云接入网络中基于容量最大化的射频拉远头选择算法设计

不同于传统的LTE-Advanced网络,云接入网络(C-RAN)通过前程链路将复杂数据处理从射频拉远头(RRH)转移至基带单元池(BBU Pool)。然而,由于C-RAN前程链路容量有限,系统总吞吐量并不一定能显著提升。在本文中,我们通过优化RRHs选择实现吞吐量的最大化。更准确地说,本文在前程容量约束条件下设计了一种选择活动RRHs集的优化算法,以实现系统容量的最大化。此外,本文分别推导了低信噪比（Low SNR）与高信噪比(High SNR)下,选择RRHs数目的渐进最优的闭合表达式。仿真结果表明,比起其他方案,本文所提出的RRH选择方案能够在有限的前程容量限制与任意给定RRHs数量下,有效实现吞吐量的提升。      

基于改进遗传算法的C-RAN网络动态无线资源分配

针对云无线网络(Cloud Radio Access Network,C-RAN)中传统静态资源分配效率低下以及动态无线资源分配中资源种类单一的问题,提出了一种基于用户服务质量(Qulity of Service,QoS)约束的动态无线资源分配方案,对无线资源从无线射频单元(Remote Radio Head,RRH)选择、子载波分配和RRH功率分配三个维度进行研究.首先,根据传统的C-RAN系统传输模型和QoS约束在时变业务环境下建立了以发射功率为变量,以吞吐量最大为优化目标的优化问题;然后,基于改进的遗传算法,将原优化方案转变为通过优化RRH选择、子载波分配和RRH功率分配来达到提高系统吞吐量的目的;最后,将改进的遗传算法与其他智能算法在种群规模变化下进行了时间复杂度对比.实验结果表明,所提算法具有较低时间复杂度,所提资源分配方案下的平均吞吐量增益为17％.     

Throughput reliability analysis of cloud‐radio access networks

This paper develops a stochastic geometry‐based analytical approach for calculating the throughput reliability of a cloud‐radio access network (C‐RAN) comprising randomly distributed remote radio heads (RRHs) and randomly located users. A tunable distance‐based RRH transmit power control mechanism along with cooperative joint transmissions by the RRHs is employed to achieve power savings and high throughput reliability. The analytical result for the throughput reliability serves as input to analysis of per user achievable average rate and C‐RAN network‐level performance metrics of spectral efficiency and energy efficiency. The analytical results are validated by Monte Carlo simulation results with good agreement, thus confirming the accuracy of the developed analytical approach. The key finding from the analysis is that by carefully tuning the RRH transmit power and cooperation parameter (cluster radius), it is possible to realize a threefold improvement in the energy efficiency along with 108% enhancement in the spectral efficiency of C‐RANs. Copyright © 2016 John Wiley & Sons, Ltd.     

TD-LTE基站射频设计技术

作为TD-LTE网络覆盖末端的射频基站,RRH对无线网络覆盖和整体网络性能影响巨大。文章针对TDD系统特点,结合当前射频技术发展情况,介绍TD-LTE射频基站系统,并对TD-LTE射频基站的关键技术以及发展方向进行研究与分析。     

云接入网中无速率编码上行传输方案

本文考虑云接入网（C-RAN）中基于无速率编码（Rateless code）的单用户上行传输系统。系统是由单用户，多个射频拉远头（RRH）以及基带处理单元（BBU）池组成。用户将要发送的信息采用无速率码进行编码并经过调制后发送；覆盖该用户的各个RRH将收到的信号进行量化后通过高速链路传输给BBU池；BBU池将收到的量化信号利用置信传播（BP）算法进行联合解压缩以及译码。为了进一步提升系统性能，我们利用外信息传递（EXIT）分析对用户无速率码度数分布进行了优化。仿真结果表明，经过度数分布优化的无速率码相较于除删信道最优度数分布在误码率（BER）和吞吐量上均有所提升，且接近理论上限。