5G光载无线通信前传系统数字预失真线性化研究

第五代移动通信系统新空口(5G NR)的信号带宽、调制度和峰均比相比4G信号高很多。用于小蜂窝或微蜂窝基站组网的光载无线通信(Radio-over-Fiber, RoF)前传系统的非线性失真也更加严重。为了使5G NR信号线性传输,采用记忆多项式(Memory Polynomial, MP)和广义记忆多项式(Generalized Memory Polynomial, GMP)模型构建数字预失真器,矫正5G RoF前传系统的非线性。在实验中搭建了2 km光纤的RoF前传系统,并采用100 MHz带宽5G NR信号作为测试信号对其进行线性化测试。实验结果表明,采用MP和GMP数字预失真器进行线性化时,5G RoF前传系统的邻信道功率比(Adjacent Channel Power Ratio, ACPR)可分别改善13 dB和17 dB以上。这说明MP和GMP数字预失真器对5G RoF前传系统的非线性具有显著的抑制作用。因此基于MP和GMP两个模型的数字预失真器均可用于5G RoF前传系统的线性化,而且GMP预失真器比MP预失真器对该系统线性化的能力更强。     

基于基站光缆网解决5G前传方案研究

本文通过分析5G前传光缆的需求与当前基站光缆网的建设特点,提出有效的使用基站光缆网满足5G前传需求的建设方案。对前期基站组网结构进行逐一分析,根据区域覆盖情况、站点情况和光缆环路情况,确定了多维的组网模型,并分别制定了相应的承载方案,以期充分利用网络资源,减少投资浪费,并能够最大限度的提升建设效率。     

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.     

CU placement over a reconfigurable wireless fronthaul in 5G networks with functional splits

Mobile network operators are currently facing a tremendous increase in the level of data traffic. Although cell size reduction is one of the most common ways used to accommodate such traffic demand, densely deployed small cells also dramatically increase the level of intercell interference. By centralizing baseband signal processing at powerful computing infrastructures, called centralized unit (CU) pools, cloud radio access network (C‐RAN) enables advanced coordination algorithms to be employed in dense small cell networks. In C‐RAN, due to stringent bandwidth and latency requirements at the fronthaul links, the optical fiber, thanks to its bandwidth and latency characteristics, continues to be the most prevalent fronthaul medium option. Nevertheless, the optical fiber is one of the fronthaul options, while C‐RAN (physical layer radio frequency [PHY‐RF] split) is one of the functional splits that can be defined each coming with different fronthaul requirements. In this paper, we formulate and solve a dynamic CU placement problem for mobile networks as an integer linear programming (ILP) problem. In the considered network, CU pools are placed at the edges of the network, and a reconfigurable millimeter wave (MMW) wireless fronthaul links are used in order to provide decentralized units (DUs) with connectivity. We study the impact of different functional splits on the placement cost and on the acceptance ratio using different substrate networks. Lastly, we propose and evaluate a CU placement heuristic algorithm using a numerical simulator. The results reveal that the optimal functional split selection can lead to significant resource utilization benefits in the RAN.     

面向5G大容量业务的超高速传输标准及技术探讨

本文从5G网络对传送网需求分析及技术标准出发,将提高线路传输速率、提升系统传输容量、软件定义光网络、光网络模块的新型应用、光网络安全保障等5个方面作为超高速传输技术的探讨方向,旨在满足5G时代大带宽、高容量和低时延的业务需求。     

A survey on role of photonic technologies in 5G communication systems

A new generation of mobile communications has been evolving for every 10 years, keeping in mind the enormous data traffic, huge capacity requirements, excellent quality of service with minimal latency; there is a shift in paradigm toward the upcoming 5G technology which is expected to be rolled out by 2020 that promises to meet the requirements stated above. 5G is envisaged to be a merged framework of wide range of applications ranging from device-to-device communications, smart grid to Internet of Things and many more. In this survey paper, a brief discussion on the major pillars of 5G which are millimeter wave technology, massive MIMO, ultra-dense network, beamforming and full-duplex transmission are presented. This survey paper also focuses on the role of optics in 5G technology, sometimes commonly referred to as microwave photonics, an interdisciplinary research platform. Due to huge bandwidth and enormous capacity upgrade, optical fibers are considered to be ideal backhaul and fronthaul media rather than copper cables in order to support small cells and next-generation networks. These advantages of optical fiber technology enable integrated optical and wireless access technologies for 5G wireless communications an interdisciplinary area of research.

     

Improved aquila optimization-based parameter evaluation framework and meta-heuristic algorithm in radio-over-fiber SpatialMux multi-input multi-output long-term evolution system

In heterogeneous access network, Multiple-Input Multiple-Output (MIMO) radio-over-fiber (RoF) system is an efficient approach for multiple signal transmission with low cost and complexity. The performance of RoF fronthaul system in MIMO system will be varied with different nonlinear effects. By adjusting various transmission parameters, such as the input signal power or the laser bias current, the nonlinear impacts produced by the RoF system can be reduced. In this paper, a novel algorithm Improved Aquila Optimization (IAO) is proposed to optimize transmission circumstances of MIMO RoF system. It determines the appropriate bias current for both lasers and Radio Frequency (RF) signal power in a short period. The input signals are wavelength multiplexed with Intensity Modulation and Direct Detection (IM/DD) applied. The carrier as well as transmission frequency is governed by the MIMO-Long-Term Evolution (LTE) standard. The proposed system is implemented in MATLAB, and the performance is evaluated. The experimental results show that fast convergence and trade-off between noise and nonlinearity are obtained with varying bandwidth. In the experimental scenario, the maximum Error Vector Magnitude (EVM) of 1.88, 3.14, and signal-to-noise ratio (SNR) of 3.204, and 2.698 was attained for both quadrature phase shift keying (QPSK) and quadrature amplitude modulation (QAM) modulation. [Correction added on 24 April 2023, after first online publication: the SNR values were corrected in the preceding sentence.] For 100 iterations, the processing time was reduced to 0.137 s. When compared with the conventional state-of-the-art approaches, the accuracy and computational complexity of the proposed approach are improved.     

面向5G前传的open-WDM新型技术架构

5G前传网络架构发生重大变化,C-RAN有望成为5G前传网络的主流组网方式。结合5G前传网络的新需求,在分析光纤直驱、无源WDM、有源WDM/OTN等现有方案的基础上,提出了面向5G前传网络的开放式波分复用（open-WDM）系统。该系统采用波分复用技术,缓解光纤资源压力;基于半有源架构,部署灵活;采用低成本管控技术,保障前传网络的可管可控和高效运维。     

高速光模块关键技术方案及标准化进展

光模块是5G承载网络、数据中心互联和全光接入网络的基础构成单元。随着上层业务应用的快速发展,高速光模块已成为各应用领域实现高带宽、广覆盖的关键要素。在梳理光模块基本概念分类及标准化整体视图的基础上,重点介绍了400Gbit/s、800Gbit/s强度和相位调制高速光模块的技术方案、标准化进展及市场发展趋势,并提出后续发展建议。     

Novel multi-band DFT-spread OFDM-PON systems based on intensity modulation and direct detection for cloud computing

Passive optical network (PON) has become a preferable access technique for cloud computing due to its elastic bandwidth capacity and transmission stability. In particular, the orthogonal frequency division multiplexing PON based on intensity modulation and direct detection (IM/DD OFDM-PON) has gained extensive attention since it is a cost- and spectral-efficient system, while for the traditional IM/DD OFDM-PON, the use of OFDM could lead to the high peak-to-average power ratio (PAPR), and it is impossible to satisfy the different QoS degrees required by ONUs under a cloud environment. Thus in this paper, we design a novel multi-band discrete Fourier transform (DFT)-spread IM/DD OFDM-PON. The DFT-spread is utilized to reduce the PAPR; meanwhile, a multi-band power allocation and bit loading are achieved to satisfy the different degrees of QoS requirement owned by ONUs. The simulation results show that our system has the better performance of PAPR reduction compared with the traditional IM/DD OFDM-PON; meanwhile, the different QoS degrees of all ONUs are guaranteed.     

基于5G网络的远程控制机器人应用及测试

通过在5G网络环境中对远程控制机器人的性能进行不同应用场景及不同网络配置下的测试与分析,验证5G网络具有的大带宽低时延等特性是否可以解决这些技术瓶颈,为远程控制协作机器人的产业发展带来新的机遇,以探索URLLC应用在真实网络中的应用性能效果及未来应用发展的优化方向。     

面向5G前传的新型CWDM承载方案

随着5G网络流量快速增长,6通道25 Gbit/s前传承载需求日趋明显。介绍了移动前传在现网部署的主要方案和标准化情况,针对6通道25 Gbit/s前传低成本承载需求,提出了一种基于CWDM/光环行器的承载方案,分析了该方案的优势与面临的挑战,介绍了该方案在实验室测试和现网试点的情况。     

Native intelligence for 6G mobile network: technical challenges,architecture and key features

The application of the artificial intelligence(AI) technology in the 5 th generation mobile communication system(5 G) networks promotes the development of the mobile communication network and its application in vertical industries, however, the application models of “patching” and “plug-in” have hindered the effect of AI applications. Meanwhile, the application of AI in all walks of life puts forward requirements for new capabilities of the future network, such as distributed training, real-time...     

Cost-effective up to 40 Gb/s transmission performance of 1310 nm directly Modulated lasers for short- to medium-range distances

This paper presents successful 20 and 40 Gb/s potentially low-cost transmission experiments using 1310 nm directly modulated distributed feedback lasers (DMLs) in the very-short- to medium-range distances. This paper will recommend operating conditions for error-free transmission at these bit rates and distances. Pattern dependencies are identified. General characteristics of direct laser modulation are confirmed by dedicated simulation software and experiments. Unknown laser parameters needed to solve the rate equations are estimated by a given method based on measured and calculated small- and large-signal DML responses.     

硅基光开关及阵列研究进展北大核心

随着网络传输数据的爆炸式增长,传统集成电路芯片面临着难以进一步提升交换速率及继续扩大容量等挑战。相较于传统电子芯片,硅基光子器件具有交换速度快、功耗低、带宽大和与CMOS工艺兼容性好等优点,可满足下一代全光交换网络、数据中心和高性能计算光互连的迫切需求,被视为在后摩尔时代突破芯片容量最具前途的解决方案,受到日益广泛关注。文章介绍了硅基光子芯片中光开关单元及阵列的技术原理和发展现状,重点论述了MZI型、MRR型开关单元,以及常见阵列拓扑结构,介绍了近年来大规模光开关阵列的国内外研究进展,讨论了未来硅基光开关及阵列研究中面临的主要问题和解决方法。     

6G网络下的全息技术发展及业务趋势

6G的研究已经在全球范围内展开,聚焦于6G网络下全息交互类业务,通过研究全息交互类场景和业务,分析了对未来网络性能的要求,进而为6G网络的设计研究和技术演进提供业务需求方面的基础。研究了全息技术与应用现状、全息通信与全息交互类场景以及场景业务的技术指标和网络性能需求。定义了全息技术的发展阶段、发展成熟度、5G下的全息产业链、全息技术应用领域分布。构建了全息类场景池、场景特征,并基于特征形成六大类应用场景。通过技术指标测算,提出了全息人像传输的带宽性能要求。     

面向5G通信网的D2D技术综述

在探讨D2D对通信技术未来发展的导向作用基础上,明确了影响D2D系统设计的多个因素,即D2D设备发现、资源分配、缓存技术、D2D-MIMO。从而勾画出基于D2D技术的光纤前传和软件定义网络实现数据/控制分离的扁平化5G架构,提出负责接入的下层宏/小基站蜂窝网和负责管理的上层网络云的管理机制。将D2D技术、SDN技术、边缘计算和物联网技术等关键技术引入未来移动通信网络已经成为研究领域的热点,针对与之相关的、未来大规模网络的移动性、QoS和大数据特性进行了讨论。     

Call Admission Control Decision Maker Based on Optimized Fuzzy Inference System for 5G Cloud Radio Access Networks

Wireless Personal Communications - In C-RAN research, different functional splits are considered for 5G mobile crosshaul networks. The typical fronthaul network based on optical fibers will be...     

5G毫米波无线网络架构及部署场景研究

5G需要满足不同场景下的应用需求,提供高带宽、大连接、低时延的能力,未来毫米波将作为5G低频段的补充,满足5G在热点区域极高的系统容量需求。本文首先分析了介绍了基于5G毫米波的发展情况及传输性能,然后分析了5G毫米波通信的三种网络架构,再结合未来可能的应用需求,提出了5G毫米波通信的主要部署场景及应用案例。     

一种基于延迟线补偿记忆效应的模拟预失真器

模拟预失真器具有带宽宽、结构简单、功耗低和延时少等优点,满足第五代移动通信系统(5G)及超 5G 的功放线性化对大带宽、低功耗和低延时的要求。然而随着移动通信系统的发展,信号的带宽和调制度越来越 高,功率放大器的记忆效应影响也越来越强,而传统的模拟预失真器无法补偿功放的记忆效应。为了解决模拟预失 真电路的记忆效应补偿问题,文中提出了一种基于延迟线补偿记忆效应的肖特基二极管模拟预失真器(SDD-APD)。 该模拟预失真器采用不等长微带线作为延迟线,用来补偿功放的记忆效应。采用100 MHz 带宽5G 新无线电(NR) 信号对工作在3. 5 GHz 的AB 类功放进行测试,结果表明该模拟预失真器可以补偿功放的记忆效应,并能将功放的 非线性改善10 dB 以上。