Power-aware virtual optical network provisioning in flexible bandwidth optical networks [Invited]

Considering the virtual network infrastructure as a service, optical network virtualization can facilitate the physical infrastructure sharing among different clients and applications that require optical network resources. Obviously, mapping multiple virtual network infrastructures onto the same physical network infrastructure is one of the greatest challenges related to optical network virtualization in flexible bandwidth optical networks. In order to efficiently address the virtual optical network (VON) provisioning problem, we can first obtain the virtual links’ order and the virtual nodes’ order based on their characteristics, such as the bandwidth requirement on virtual links and computing resources on virtual nodes. We then preconfigure the primary and backup paths for all node-pairs in the physical optical network, and the auxiliary graph is constructed by preconfiguring primary and backup paths. Two VON mapping approaches that include the power-aware virtual-links mapping (PVLM) approach and the power-aware virtual-nodes mapping (PVNM) approach are developed to reduce power consumption for a given set of VONs in flexible bandwidth optical networks with the distributed data centers. Simulation results show that our proposed PVLM approach can greatly reduce power consumption and save spectrum resources compared to the PVNM approach for the single-line rate and the mixed-line rate in flexible bandwidth optical networks with the distributed data centers.     

Providing differentiated service to TCP flows over bandwidth on demand geostationary satellite networks

The elasticity of transmission control protocol (TCP) traffic complicates attempts to provide performance guarantees to TCP flows. The existence of different types of networks and environments on the connections' paths only aggravates this problem. In this paper, simulation is the primary means for investigating the specific problem in the context of bandwidth on demand (BoD) geostationary satellite networks. Proposed transport-layer options and mechanisms for TCP performance enhancement, studied in the single connection case or without taking into account the media access control (MAC)-shared nature of the satellite link, are evaluated within a BoD-aware satellite simulation environment. Available capabilities at MAC layer, enabling the provision of differentiated service to TCP flows, are demonstrated and the conditions under which they perform efficiently are investigated. The BoD scheduling algorithm and the policy regarding spare capacity distribution are two MAC-layer mechanisms that appear to be complementary in this context; the former is effective at high levels of traffic load, whereas the latter drives the differentiation at low traffic load. When coupled with transport layer mechanisms they can form distinct bearer services over the satellite network that increase the differentiation robustness against the TCP bias against connections with long round-trip times. We also explore the use of analytical, fixed-point methods to predict the performance at transport level and link level. The applicability of the approach is mainly limited by the lack of analytical models accounting for prioritization mechanisms at the MAC layer and the nonuniform distribution of traffic load among satellite terminals.     

Adaptive DC interconnection provisioning in distributed all-optical micro-datacenters using holistically SDN orchestration for dynamic access

The metro-embedded datacenter (ME-DC) architecture which is based on micro-DCs (mDC) is introduced and implemented to deliver more flexible services with less access latency. Hierarchical SDN control is employed to adaptively interconnect the distributed mDCs and the metro network slices into re-configurable virtual DC (VDC). Such an approach improves the overall resource mobility, especially for traveling users that need to dynamically access the service. In this paper, the VDC re-configuration and pre-configuration mechanisms for dynamic user access are proposed and demonstrated for the first time. In specific, by re-configuring the VDC with the most accessible resources with user location tracking, fast and flexible service is provided with consistent service access. Furthermore, by pre-configuring the VDC with user prediction, mDC and metro network resources are reserved in advance for users in order to provide seamless service. Demonstration based on the implemented ME-DC prototype shows that VDC is adaptively constructed for dynamic user access with fast and flexible service provisioning.     

Analysis of upstream link bandwidth utilization in GPON with integrated network surveillance

We present a media access control protocol extension to integrate the physical layer surveillance concept into the transmission and the related management system in the Gigabit-capable passive optical network (GPON). We allocate an unused time slot for network surveillance depending upon its availability in the upstream GPON transmission convergence frame. We analyze the upstream link bandwidth utilization of the GPON system with network surveillance and show that there is a negligible amount of underutilization of link bandwidth as a result of this.     

信息资源网络化对信息服务的影响

介绍了信息资源网络化与信息服务业的联系，通过对目前网络资源管理上的几方面趋势分析，探讨信息资源网络化对信息服务在各方面产生的影响，并针对每一种趋势提出信息资源管理研究需要注意和探讨的一些问题。     

一种基于SDN的移动自组织网络服务路径重建算法

针对基于SDN的移动自组织网络链路故障时的服务路径重建问题,提出一种服务路径分级重建方法,通过备份重建和计算重建相结合的过程提高了服务路径重建的时效性;同时,考虑服务路径重建可能引发的路径冲突问题,从图论的基本原理出发,给出了完备的判定重建定理,在快速重建的基础上亦保证重建服务路径的有效性。     

On service provisioning using light-trails in WDM optical networks with waveband switching

As the number of wavelengths in a single optical fiber increases, so does the number of ports needed for wavelength switching in optical cross-connects (OXCs), which may significantly increase the cost and difficulty associated with controlling large OXCs. Waveband switching (WBS) treats several wavelengths as a bundle that is switched through a single port if they share the same switch route, so that the number of ports needed can be reduced. On the other hand, light-trails in wavelength division multiplexing (WDM) optical networks allow intermediate nodes on established optical paths to access the data paths whereas light-paths only allow two end nodes to access the data paths. Therefore, light-trails offer significantly better flexibility for service provisioning and traffic grooming. In this article, we study service provisioning using light-trails in WDM optical networks with the WBS capability under a static traffic model. For comparison, integer linear programs are formulated for establishing light-trails with and without WBS. Numerical studies show that in certain cases, service provisioning with WBS in light-trail networks can reduce the number of ports needed while providing a more flexible sub-wavelength service provisioning capability. However, contrary to intuition, in most cases applying the WBS technique requires more ports in OXCs in light-trail networks. This study provides insights into the network design problem that applies the WBS technology to light-trail based optical networks.     

A network flow approach to memory bandwidth utilization in embedded DSP core processors

This paper presents a network flow approach to solving the register binding and allocation problem for multiword memory access DSP processors. In recently announced DSP processors, 16-bit instructions which simultaneously access four words from memory are supported. A polynomial-time network flow methodology is used to allocate multiword accesses, including constant data-memory layout, while minimizing code size. Results show that improvements of up to 87% in terms of memory bandwidth are obtained compared to compiler-generated DSP code. This research is important for industry since this value-added technique can improve code size and utilize higher-memory bandwidths without increasing cost.     

一种均衡物理资源和网络带宽的虚拟机部署方法研究

随着互联网的发展,云计算的发展越来越快,云资源管理平台也受到了越来越多的关注。云计算资源管理系统是云计算体系的大脑,具有重要的研究价值。针对目前虚拟机部署未能均衡考虑能耗与网络流量的问题,文章设计了一种结合能耗和网络均衡优化的虚拟机部署算法。该算法采用K-均值聚类,利用改进的皮尔逊相关系数进行相似度计算,最终为虚拟机在所有的候选宿主机中选择合适的宿主机。     

基于DirectShow的网络视频点播系统的设计与实现

随着计算机技术和Internet日新月异的的发展,宽带VOD视频点播技术因其良好的人机交互性和流媒体传输技术倍受教育、娱乐等行业的青睐。设计了一种基于Direct Show技术的视频点播系统,该系统采用VC编程语言实现,基于C/S架构搭建通信网络,通过套接字实现多台客户机与服务器间的通信。测试结果表明,系统能够正常运行,视频播放流畅,可以满足网络视频点播的需求。     

VoIP over DVB-RCS with QoS and bandwidth on demand

Motivated by the need for compliance/interoperability above the satellite-specific layers, this article proposes a consolidated approach for voice over IP over satellite networks based on the ETSI DVB-RCS standard. Voice communication is a real-time service that needs priority over other services in IP environments with limited bandwidth, such as IP satellite networks. Bandwidth utilization in such networks needs to be optimized in order to reduce service costs, and this requires the use of dynamic bandwidth allocation schemes. This article therefore addresses the role of bandwidth on demand in the optimization of bandwidth allocation for VoIP and assesses the impact of BoD mechanisms on voice quality. The trade-off between voice quality and bandwidth efficiency is investigated under different DVB-RCS-specific capacity request/allocation strategies, and it is demonstrated that DVB-RCS provides an efficient platform for integrated support for a variety of VoIP applications over satellite. The main contribution of this article consists of the identification of the mechanisms capable of responding to the key challenges raised by the VoIP application in the satellite environment.     

提高乡镇3G网络无线资源利用率的分析及研究

随着3G建设的发展,郊区乡镇普遍存在3G资源利用率低、2G/3G话务不均衡、3G用户回落2G网络比例较高等情况.对乡镇3G基站运行情况进行了分析,并提出了优化整改方案和思路,通过实际案例表明该方案可以有效提高乡镇3G基站的资源利用率、平衡2G/3G话务负荷,对于后期的3G以及4G建站模式具有一定的参考价值.     

Quality-of-service provisioning and efficient resource utilization in CDMA cellular communications

One of the major challenges in supporting multimedia services over Internet protocol (IP)-based code-division multiple-access (CDMA) wireless networks is the quality-of-service (QoS) provisioning with efficient resource utilization. Compared with the circuit-switched voice service in the second-generation CDMA systems (i.e., IS-95), heterogeneous multimedia applications in future IP-based CDMA networks require more complex QoS provisioning and more sophisticated management of the scarce radio resources. This paper provides an overview of the CDMA-related QoS provisioning techniques in the avenues of packet scheduling, power allocation, and network coordination, summarizes state-of-the-art research results, and identifies further research issues.     

Supporting multi-user real-time VBR video service using dynamic bandwidth management based on prediction

Real-time variable bit rate (VBR) video is expected to take a significant portion of multimedia applications. However, plentiful challenges to VBR video service provision have been raised for its characteristic of high traffic abruptness. To support multi-user real-time VBR video transmission with high bandwidth utilization and satisfied quality of service (QoS), this article proposes a practical dynamic bandwidth management scheme. This scheme forecasts future media rate of VBR video by employing time-domain adaptive linear predictor and using media delivery index (MDI) as both QoS measurement and complementary management reference. In addition, to support multi-user application, an adjustment priorities classified strategy is also put forward. Finally, a test-bed based on this management scheme is established. The experimental results demonstrate that the scheme proposed in this article is efficient with bandwidth utilization increased by 20%-60% compared to a fixed service rate and QoS guaranteed.     

VoLTE自动开通成功率提升优化与应用

VoLTE自动开通是为了便捷用户开通VoLTE业务、降低用户开通业务的门槛而提供的解决方案,即当用户使用4G USIM卡,且终端支持VoLTE语音功能时,网络侧将主动触发支撑侧的VoLTE业务开通流程。随着全网用户的承载,VoLTE自开通成功率成为影响VoLTE进一步深化推广的重要因素。基于某一电信运营商的VoLTE自动开通流程,分析了导致VoLTE自开通成功率偏低的主要原因,针对跨域数据不一致、特殊用户不允许开通业务、BOSS内部处理超时等问题,提出了优化思路和方案,实施后数据表明对VoLTE自开通成功率显著提升至95%,并对行业内解决类似自动开通问题具有一定指导性和参考性。     

基于网格化的移动通信网络资源与业务发展评估分析

在当前5G网络大规模建设、4G网络建设大幅缩减的情况下,针对当前主流运营商网络运营维护网格化的现状,为保障4G网络长久运营,需进一步加强4G网络建设精准性及提升4G投资效益.本文结合当前网络资源和业务发展都是网格化管理的现状,针对性地对4G网络网格内网络资源与市场发展匹配情况进行网格化分析,精准评估区分制约网格业务发展...     

Efficient bandwidth allocation and call admission control for VBR service using UPC parameters

Provision of Quality‐of‐Service (QoS) guarantees is an important and challenging issue in the design of Asynchronous Transfer Mode (ATM) networks. Call Admission Control (CAC) is an integral part of the challenge and is closely related to other aspects of network designs such as traffic characterization and QoS specification. Since the Usage Parameter Control (UPC) parameters are the only standardized traffic characterizations, developing efficient CAC schemes based on UPC parameters is significant for the implementation of CAC on ATM switches. In this paper, we develop a CAC algorithm called TAP (derived from TAgged Probability) as well as two other CAC algorithms using the UPC parameters. These CAC algorithms are based on our observation that the loss‐probability‐to‐overflow‐probability ratio tends to decrease as the number of sources increases. By introducing the loss‐probability‐to‐overflow‐probability ratio K, we find that this ratio sheds light on increasing resource utilization while still guaranteeing QoS. Analysis, simulation, and numerical results have shown that the proposed TAP algorithm is simple and efficient. Copyright © 2000 John Wiley & Sons, Ltd.     

基于SDN的网络虚拟化平台及其隔离性研究

随着云计算的高速发展,虚拟化正成为近年来在企业级环境下广泛应用的技术。除服务器及存储虚拟化外,在SDN和OpenFlow技术的推动下,网络虚拟化成为热点,基于SDN的网络虚拟化平台也应运而生。在分析基于SDN的网络虚拟化设计目标的基础上,对近年来业界推出的4种典型SDN网络虚拟化平台的系统架构和原理进行了对比,并对其安全和隔离性进行了分析总结。     

基于SDN的工业无线网络能量高效型路由算法

在智能制造背景下,为了提高无线网络的灵活性和能量使用效率,提出基于软件定义网络(SDN)的工业无线网络能量高效路由算法(SDERA)。基于SDN数据平面和控制平面分离的思想,构建了新型的工业无线网络模型,控制器根据应用需求、节点的剩余能量和负载等因素,计算全局最优路由策略并分发给交换节点,交换节点按照控制器的决策在不同的逻辑子网中转发数据包。当节点和链路质量信息以及应用需求发生变化时,控制器可以动态地调整路由策略,提高能量使用效率和网络性能。仿真实验结果表明,该路由算法有效地延长了网络的生存时间,提高了网络的能量使用效率。