Energy Efficient Wireless Networks Towards Green Communications

Wireless networks have become an essential part of the modern life. However, currently, 3% of the world-wide energy is consumed by the ICT infrastructures which causes about 2% of the world-wide CO₂ emissions. The transmitted data-volume increases rapidly and wireless communications are used extensively while network design rules have practically ignored the energy efficient network design approach to limit CO₂ emissions. This approach is currently named Green Communications. Significant energy savings in mobile networks can be expected by defining and standardizing energy efficiency metrics and combining energy aware flexible radios and networks. This paper discusses several techniques such as cross layer approach, multiple antennas, cell size reduction and cognitive radio, from the system-wide energy efficiency point of view, outlining challenges and open issues.     

IP优化的下一代光通信网络

文章分析了未来通信网的两大发展趋势——宽带化和数据化,对基于IP的DWDM宽带光联网技术的国内外发展现状作了较为详尽的介绍。     

Network Design and Architectures for Highly Dynamic Next-Generation IP-Over-Optical Long Distance Networks

The DARPA CORONET project seeks to develop the target network architectures and technologies needed to build next-generation long-distance IP-over-Optical-Layer (IP/OL) networks. These next-generation networks are expected to scale 10–100 times larger than today's largest commercial IP/OL network. Furthermore, DARPA has established advanced objectives for very rapid provisioning of new IP or private line connections, very rapid restoration against up to three simultaneous network failures, and future dynamic “wavelength” services ranging from speeds of 40–800 Gigabits per second. Besides these ambitious goals, the CORONET project seeks to establish a commercially-viable network architecture that supports both commercial and government services. In this paper, we describe the CORONET program requirements, and present our initial architectures and analysis of the early phases of this long-term project. We propose a novel 2-Phase Fast Reroute restoration method that achieves 50–100 ms restoration in the IP-Layer in a cost-effective manner, and a commercially viable OL restoration method that can meet the rapid CORONET requirements. We also estimate the magnitude of the extra capacity needed to provide dynamic wavelength services compared to that of static services, and show that the extra capacity to restore a small percentage of high priority traffic against multiple failures requires a small amount of extra capacity compared to that of single failures.      

Enabling Technologies for Next-Generation Optical Packet-Switching Networks

The optical packet-switching network is considered to be one of the most promising solutions for end-to-end delivery of high-bitrate data, video, and voice signals across optical networks of the future. Optical label switching (OLS) technology incurs simpler extraction and processing of the labels so that the optical packets can be routed with low latency to the destinations. We have developed several key enabling technologies for integrated optical networks, including optical label generation, label swapping, optical buffering, clock recovery, and wavelength conversion. We have designed and experimentally demonstrated these enabling techniques that can provide efficient broadband services in future optical networks.     

下一代无线接入网--基于IP的无线接入

下一代无线网络的体系结构标准正在制定中,本文介绍了一种基于IP的网络体系结构,它可以作为不同接入技术的通用接入网。这种基于IP的无线接入网采用Intemet标准和Mobile IP协议支持移动终端的宏移动,当移动终端只做微移动或需实现无线呼叫功能时,就采用HAWAII协议。在网络部署规模日益增长的情形下,基于IP的无线接入在网间互连互通等方面表现出了明显的优势。     

下一代网络的新业务开发技术

快速和简便的开发新业务是下一代网络的要求和推动力，不同的方法适合不同情况的业务开发，本文结合实例介绍了几种方法，说明了业务开发步骤，描绘了下一代网络新业务开发技术的框架。     

Layer 1 Virtual Private Networks in Multidomain Next-Generation Networks

High-capacity e-science and consumer applications require transport networks that are dynamically provisioned. Rapid advances in next-generation SONET/SPH and optical switching along with GMPLS control have enabled many new services' provisioning capabilities. In particular, a key paradigm is the new layer 1 virtual private network framework, which allows clients to directly provision their own services without deploying expensive infrastructures. This article presents an overview of L1-VPN and describes a resource management scheme that will enable transport network virtualization across a multidomain network infrastructure. The scheme is implemented in both centralized and distributed control frameworks, and allows for dynamic sharing of transport resources. A case study of performance analysis results is presented showing a distributed control plane in a multidomain network architecture achieving higher VPN carrying capacity than a centralized control plane     

A Remotely Reconfigurable Remote Node for Next-Generation Access Networks

A remotely reconfigurable remote node (RN) for next-generation (NG) access networks is proposed and demonstrated. The RN is remotely reconfigured by instantaneous optical powering at the central office through feeder fiber and maintained in a passive state by employing optical latching switches (OLSs). The feasibility of the proposed RN is demonstrated by investigating the operating conditions of optical powering for the reconfiguration and its nonlinear effect both for time-division-multiplexing passive optical network (TDM-PON) as legacy services and wavelength-division-multiplexing passive optical network (WDM-PON) as NG services. The existence of OLSs for reconfigurability and crosstalk effect between TDM-PON and WDM-PON are negligible on transmission performance.     

Seamless Maintenance and Protection Scheme for Next-Generation Access Networks

We propose and demonstrate a seamless maintenance and protection scheme based on remotely reconfigurable remote node. Protection for fiber failures and a centralized optical time-domain reflectometry test for preventive maintenance can be achieved within 90 ms by using instantaneous optical powering at the central office, while maintaining the passive nature of the passive optical network.      

下一代手机设计的集成技术

为了满足对于高度集成的无线电半导体解决方案日益增长的需求，蜂窝电话的技术创新正在沿着两个不同的方向发展。其一是在芯片级和封装级的功能集成，其二是完整的半导体系统解决方案。后者将所有必须的芯片、模块和软件捆绑到一个全面的解决方案中，从而简化了设计步骤．加快了产品进入市场的时间。     

一种适用于下一代网络中应用服务器的过载控制算法

本文介绍了下一代网络中应用服务器的概念及其过载控制问题,分析了对过载控制新的要求,提出了应用服务器过载控制框架.在此基础上,给出了算法指标、过载检测方法和过载控制算法.理论分析和仿真结果表明本文提出的过载控制算法具有良好的有效性和公平性.     

基于FTTx的下一代通信网精确覆盖系统的设计与实现

在"宽带中国"上升为国家战略的大背景下,有效支撑移动宽带和固定宽带业务的发展是当前及今后一段时期通信网络转型的一项重大举措,也是室内深度覆盖建设转型的契机。通过探讨基于FTTx的下一代通信网精确覆盖系统的设计、系统基本原理、硬件电路原理及系统硬件实现等方面,为各运营商在无线网室内精确覆盖方案的制定提供一定的参考。     

Adaptive Opportunistic Multicast Scheduling Over Next-Generation Wireless Networks

This paper considers the problem of opportunistic multicast scheduling in wireless time-division multiplexing systems with adaptive modulation and channel coding. The problem is first formulated and an effective scheduling scheme is proposed to maximize the multicast throughput while a desired packet error rate is guaranteed. The proposed scheme dynamically selects multicast rates by considering the configuration of the multicast group and instantaneous network states, and thus it can adapt well to network conditions. Extensive simulation results conclusively demonstrate that, compared to the worst-user multicast scheduling, the proposed approach can increase the wireless channel efficiency by large margins, especially when the channel is operating in a lower signal-to-noise ratio region and/or when the multicast group size increases. Besides, the simulations show that the proposed approach can work well in systems with imperfect channel estimation.     

Distributed Medium Access Control Next-Generation CDMA Wireless Networks

The next-generation wireless networks are expected to have a simple infrastructure with distributed control. In this article, we consider a generic distributed network model for future wireless multimedia communications with a code-division multiple access (CDMA) air interface. For the medium access control (MAC) of the network model, we provide an overview of recent research efforts on distributed code assignment and interference control and identify their limitations when applied in next-generation wireless networks supporting multimedia traffic. We also propose a novel distributed MAC scheme to address these limitations, where active receivers determine whether a candidate transmitter should transmit its traffic or defer its transmission to a later time. Simulation results are given to demonstrate the effectiveness of the proposed distributed MAC scheme.     

从3G-WLAN融合看基于IMS的网络融合架构

下一代网络是一个融合的网络.目前受到业界大力推崇的是基于IP多媒体子系统（IMS）的网络融合架构,而3GPP-WLAN网络的融合最有可能成为该架构的先行者.文章首先分析3GPP R6规范中的3GPP-WLAN融合方案,然后以此为范例,给出了基于IMS实现固定和移动融合（FMC）的下一代网络的参考架构.     

Sub-Wavelength Solutions for Next-Generation Optical Networks [Topics in Optical Communications]

The recent trend in optical networks is switching packets directly in the optical domain. The aim is to benefit from both packet flexibility and optical transparency. In this article, we review current optical architectures that try to reconcile these two requirements. We discuss the challenges encountered in these new architectures and their respective niches. To meet the requirements of next-generation high-speed optical networks, we also propose a new solution based on the distribution of the aggregation process in the network. The feasibility of this scheme and the benefit that it provides over existing solutions are analyzed in this article.     

Prospects for a Next-Generation Deep-Space Network

A next-generation deep-space network is currently under consideration by the National Aeronautics and Space Administration. Building upon its many past successes, this network will be required to meet the needs of current and planned missions. These will, no doubt, include the familiar suite of telemetry, command, tracking, and navigation services, with performance levels derived from analysis of the probable future mission set. Additionally, it will be expected to provide enabling capabilities for missions still on the drawing boards. Traditionally, the network serves the robotic deep-space exploration fleet. However, at this time, consideration of the special needs of planned future human lunar missions is appropriate, as well as the evolution to the eventual human exploration of Mars.