ITU-T有关EOT功能架构的标准与关键技术

本文根据最新的ITU-T研究进展,介绍、分析和总结了有关传送网承载以太网的传送功能架构,包括传送网分层网络模型的描述;以太网的分层结构与各层特征信息的详细描述;以太网的OTN/ETH等各类适配功能的分析、总结,网络拓扑结构的简要分析,以及相关标准的历史进程介绍.     

SDH传送网结构

本文介绍了ＳＤＨ传送网结构的基本概念、网络结构元件、网络的分层和分割以及ＳＤＨ传送网分层模型。最后还提出了我国ＳＤＨ的网络拓扑结构的初步考虑。     

广域以太网:迈向电信级之路

本文在给出了广域以太网定义和对发展原因分析的基础上，重点分析广域以太网的相关问题，包括扩展性、业务模型、质量保证和以太网OAM等，并就广域以太网的发展前景做了简单探讨。     

运营商级以太网及传送网的转型

本文分析了业务IP化给传送网所带来的挑战,并阐述了传送网中应对这种业务转型而发展出的运营商级以太网技术及分组化转型趋势,最后简单介绍了阿尔卡特朗讯基于对传送网转型的理解所开发的全业务交换传送平台1850TSS系列。     

城域传输网网络结构的演进

城域传输网一般可分为三层结构:①核心层:由核心节点组成,一般包括交换局、长途局、数据中心及关口局等,负责核心节点间大容量中继电路与省/本地长途网以及其它网络的互联互通;②汇聚层:由汇聚节点组成,负责     

Throughput-range tradeoff of wireless mesh backhaul networks

Wireless backhaul communication is expected to play a significant role in providing the necessary backhaul resources for future high-rate wireless networks. Mesh networking, in which information is routed from source to destination over multiple wireless links, has potential advantages over traditional single-hop networking, especially for backhaul communication. We develop a linear programming framework for determining optimum routing and scheduling of flows that maximizes throughput in a wireless mesh network and accounts for the effect of interference and variable-rate transmission. We then apply this framework to examine the throughput and range capabilities for providing wireless backhaul to a hexagonal grid of base stations, for both single-hop and multihop transmissions for various network scenarios. We then discuss the application of mesh networking for load balancing of wired backhaul traffic under unequal access traffic conditions. Numerical results show a significant benefit for mesh networking under unbalanced loading.     

Spectrum allocation for wireless backhaul in heterogeneous ultra-dense networks

Wireless ultra-dense network (UDN) is one of the important technologies to solve the burst of throughput demand in the forthcoming fifth generation (5G) cellular networks. Reusing spectrum resource for the backhaul of small base stations (SBSs) is a hotspot research because of lower cost and rapid implementation with macro base stations (MBSs) in recent years. In heterogeneous UDN, the problem of spectrum allocation for wireless backhaul is investigated. In particular, two different spectrum resource reusing strategies for wireless backhaul are proposed in heterogeneous UDN with the limited bandwidth condition. Using a stochastic geometry-based heterogeneous UDN model, the success probabilities that mobile users communicate with SBSs or MBSs are derived under two different spectrum resource reusing strategies. In addition, the network throughput’s analytical expressions and the optimal ratio of spectrum allocation are derived. Numeral results are provided to evaluate the performance of the proposed strategies at throughput. Thus, the effectiveness of the strategy that mobile users can only communicate with SBSs is validated.     

VLSI Node Processor Architecture for Ethernet

The VLSI Ethernet controller chips are discussed from a designer's viewpoint. Their method of operation is explained and design tradeoffs are presented with concentration placed on memory response requirements, memory location options relative to the VLSI devices, and the effects of FIFO depth on performance. A "common sense" architecture for an Ethernet node processor with application to many classes of Ethernet nodes is suggested to conclude the paper.     

Designing multihop wireless backhaul networks with delay guarantees

As wireless access technologies improve in data rates, the problem focus is shifting towards providing adequate backhaul from the wireless access points to the Internet. Existing wired backhaul technologies such as copper wires running at DSL, T1, or T3 speeds can be expensive to install or lease, and are becoming a performance bottleneck as wireless access speeds increase. Longhaul, non-line-of-sight wireless technologies such as WiMAX (802.16) hold the promise of enabling a high speed wireless backhaul as a cost-effective alternative. However, the biggest challenge in building a wireless backhaul is achieving guaranteed performance (throughput and delay) that is typically provided by a wired backhaul. This paper explores the problem of efficiently designing a multihop wireless backhaul to connect multiple wireless access points to a wired gateway. In particular, we provide a generalized link activation framework for scheduling packets over this wireless backhaul, such that any existing wireline scheduling policy can be implemented locally at each node of the wireless backhaul. We also present techniques for determining good interference-free routes within our scheduling framework, given the link rates and cross-link interference information. When a multihop wireline scheduler with worst case delay bounds (such as WFQ or Coordinated EDF) is implemented over the wireless backhaul, we show that our scheduling and routing framework guarantees approximately twice the delay of the corresponding wireline topology. Finally, we present simulation results to demonstrate the low delays achieved using our framework.     

A Fault Tolerant Hierarchical Network on Chip Router Architecture

Continuing advances in the processing technology, along with the significant decreases in the feature size of integrated circuits lead to increases in susceptibility to transient errors and permanent faults. Network on Chips (NoCs) have come to address the demands for high bandwidth communication among processing elements. The structural redundancy inherited in NoC-based design can be exploited to improve reliability and compensate for the effects of failures. In this paper, we propose an enhanced fault tolerant microarchitecture with deadlock-free routing for Hierarchical NoCs. The proposed router supplies dynamic Virtual Channel (VC) Allocation, and it employs a high-performance fault tolerant control flow, handling both transient and permanent faults in hierarchical networks without extra retransmission buffer requirements. Experimental results show a significant improvement in reliability as well as decreases in the average latency and energy consumption.     

5G无线网络架构对传输网的影响

为了满足3种5G典型业务的覆盖和容量的需求,5G网络中引入了非独立和独立部署4G和5G组网架构以及集中单元(CU)/分布单元(DU)分离的设备形态。新的无线网络架构对于未来传输网的部署也提出了新的挑战。基于当前5G网络架构的标准进展,从无线网络的角度分析了5G网络架构对传输网的影响和需求。     

一种基于多频分级架构的空中自组网研究

随着节点的增加和应用类型的丰富,如何实现众多空中节点自由组网已经迫在眉睫,基于分布式架构的移动Ad hoc技术被认为是解决该问题的有效途径。本文在分析飞机编队特征的基础上,提出了一种包括组网架构、分级式路由协议CDAR等在内的飞机组网方案。仿真结果表明,该方案能使网络的性能更优。     

Joint backhaul bandwidth and power allocation in heterogeneous cellular networks: A two‐level approach

We investigate the problem of joint downlink wireless backhaul bandwidth (WBB) and power allocation in heterogeneous cellular networks (HCNs). A WBB partitioning scheme is considered, which allocates the whole bandwidth between the macrocell and small cells for data transmission and backhauling. We formulate an optimization problem to maximize the weighted sum logarithmic utility function by jointly optimizing WBB portion and fronthaul power allocation of each base station with consideration of the backhaul capacity limitation on each small cell. In order to solve this joint optimization problem, we propose a hierarchical two‐level approach and decompose the original problem into two independent subproblems: the WBB allocation at the macrocell base station (MBS) and the power allocation at both the MBS and small cell base stations (SBSs). Accordingly, the optimal WBB portion and power allocation solutions are obtained, respectively. Furthermore, we develop a distributed algorithm to implement the joint WBB and power allocation. Numerical results verify the effectiveness of the proposed approach and analyze the impact of the weighted coefficient and backhaul capacity limitation on the network performance. In addition, significant performance gains can be achieved by the proposed approach over the benchmark.     

Hybrid beamforming with discrete phase shifters for millimeter wave backhaul networks

Hybrid beamforming (HBF) technology becomes one of the key technologies in the millimeter wave (mmWave) mobile backhaul systems, for its lower complexity and low power consumption compared to full digital beamforming (DBF). Two structures of HBF exist in the mmWave mobile backhaul system, namely, the fully connected structures (FCS) and partially connected structures (PCS). However, the existing methods cannot be applied to both structures. Moreover, the ideal phase shifter is considered in some current HBF methods, which is not realistic. In this paper, a HBF algorithm for both structures based on the discrete phase shifters is proposed in the mmWave mobile backhaul systems. By using the principle of alternating minimization, the optimization problem of HBF is decomposed into a DBF optimization problem and an analog beamforming (ABF) optimization problem. Then the least square (LS) method is enabled to solve the optimization model of DBF. In addition, the achievable data rate for both structures with closed-form expression which can be used to convert the optimization model into a single-stream beamforming optimization model with per antenna power constraint is derived. Therefore, the ABF is easily solved. Simulation results show that the performance of the proposed HBF method can approach the full DBF by using a lower resolution phase shifter.     

面向5G的传送网新架构及关键技术

面向5G的传送网面临大带宽、低时延、网络分片、灵活连接、高精度时间同步、组网架构变化等多方面的技术挑战。指出了分组传送网(PTN)、基于IP的无线接入网(IPRAN)、光传送网(OTN)等现有技术难以完全满足5G的长远需求,灵活以太网(FlexE)、灵活光传送网(FlexO)、分段路由(SR)、软件定义网络(SDN)等新技术为5G承载提供了新的选择,基于25 G的光管芯也逐渐成为了高速光通信的基础。认为5G为新的传送网技术的引入提供了重要驱动和时间窗口,并首次提出了将切片分组网(SPN)体系架构用作5G前传、中传和回传的统一承载,同时还对其关键技术做了介绍。     

Flex Ethernet Technology and Application in 5G Mobile Transport Network

With the advent of 5G era,the rise of cloud services,virtual reality/virtual reality(AR/VR),vehicle networking and other technologies has put forward new requirements for the bandwidth and delay of the bearer network.Traditional Ethernet technology cannot meet the new requirements very well.Flex Ethernet(FlexE)technology has emerged as the times require.This paper introduces the background,standardization process,functional principle,application mode and technical advantages of FlexE technology,and finally analyses its application prospects and shortcomings in 5G mobile transport network.     

Multi-hop wireless backhaul networks: a cross-layer design paradigm

Multihop wireless backhual networks are emerging as a cost-effective solution to provide ubiquitous and broadband access to meet the rapidly increasing demands of multimedia applications. In this paper, we consider the joint optimal design of routing, medium access control (MAC) scheduling and physical layer resource allocation for such networks, where beamforming antenna arrays are equipped at the physical layer. The notion of transmission set (TS) is introduced to separate the physical layer operations from those at the upper layers; and a column generation approach is employed to efficiently identify the TSs. We then apply the dual decomposition method to decouple the routing and scheduling subproblems, which are performed at different layers and are coordinated by a pricing mechanism to achieve the optimal overall system objective. To efficiently support multimedia traffic, an admission control criterion is considered for the system objective. The performance of the proposed scheme is verified by simulation results, and the impact of the physical layer capabilities on the network performance is evaluated. We also discuss the implementation issues of the cross-layer scheme based on the IEEE 802.16 mesh mode.     

Architecture to integrate multiple PONs with long reach DWDM backhaul

This paper demonstrates the feasibility of an architecture that consolidates a number of deployed Passive Optical Network (PON) infrastructures into a long-reach, high-split ratio system which further increases equipment sharing between users. The demonstrated system allows the use of uncooled lasers with possible wavelength drift across a CWDM band (20 nm) with optical amplification and narrow optical filtering with no performance degradation. A complete study of potential implementations was performed with experimental results showing that a target performance of 10^-10 could be achieved over 120 km of standard fiber with transmitter wavelengths from 1542 to 1558 nm and DWDM backhaul wavelengths from 1520 to 1535 nm. This gives the potential to support up to 2560 users.     

基于双频网和分层体系的GSM立体网络及其应用实践

文章分析GSM数据流量激增的原因,介绍解决网络高负荷的应对策略。面向网络建设,从兼顾网络结构、规则调整及降低干扰的角度出发,提出基于GSM双频网和分层体系的高话务密度区立体网络建设策略,详细说明双频网的规划方法和建设原则,并从覆盖和容量两个维度对该立体网络架构性能提升进行了分析与探讨。     

Fair inter‐TAP routing and backhaul assignment for wireless mesh networks

Although limiting the number of backhauls, specifically chosen transit access points (TAPs) that forward traffic from other TAPs, reduces the overall costs of a wireless mesh network (WMN), an egress bottleneck is induced, which aggregates traffic and limits the bandwidth. To avoid such problems while working to minimize budgetary expenses, we balanced traffic flow on ‘to‐be‐determined’ backhauls and adjacent links, a mixed nonlinear‐and integer‐programming problem that minimizes the aggregated flow subject to budget, backhaul assignment, top‐level load‐balanced routing, and link capacity constraints. Two algorithms are proposed, weighted backhaul assignment (WBA) and greedy load‐balanced routing (GLBR), that operate in conjunction with Lagrangean relaxation (LR), used for constructing LR‐based heuristics and also as a means of quantification and evaluation of the proposed algorithms. Experiment results show that the proposed algorithms achieve near‐optimization, outperforming related solutions. Copyright © 2008 John Wiley & Sons, Ltd.