AMRST: adaptive multicast routing protocol for satellite–terrestrial networks

Multicasting facilitates the distributing of multimedia information to an entire set of destinations simultaneously. However, the subsequent mass of Internet traffic usually increases the network congestion and degrades network utilization. The unexpected congestion together with limited network capacity might challenge the provision of multimedia services especially since multicast subscribers are widely scattered. The desired QoS of the ongoing services cannot be guaranteed. To address this challenge, in addition to installing new terrestrial broadband networks, another feasible solution would be to integrate now available broadcasting-oriented broadband satellite networks into the Internet backbone. This paper presents a novel adaptive multicast routing (AMRST) protocol to deliver reliable and adaptive multicast services to global subscribers, based on an integrated infrastructure, called a satellite–terrestrial network (ST network), which provides dynamic bandwidth allocation, flexible resource management and ubiquitous transmission. In the AMRST, a proposed virtual hierarchical routing tree was applied in constructing an efficient multicast tree. A routing decision model was proposed to determine routing path for the member requests. A “hierarchical membership maintenance” approach was designed to maintain the multicast membership. The scalability of the AMRST was further addressed. The AMRST not only kept the benefits of the traditional terrestrial multicast but also promoted the multicasting performance by employing the satellite broadcasting capability. The simulation results demonstrate that the AMRST performed excellently for the ST network.     

基于VxWorks的宽带电台控制协议实现

战术互联网中宽带电台通常可以通过网口与互联网控制器连接,在使用中由互联网控制器通过专门的控制协议对电台参数进行设置,以满足通讯要求。给出了在V xW orks操作系统下,在MUX层实现宽带电台控制协议的一种方法。     

Performance evaluation for underlay cognitive satellite-terrestrial cooperative networks

With the continuously increasing demand for broadband applications and services, underlay cognitive satellite-terrestrial networks, enabling to accommodate better wireless services within the scarce spectrum, have attracted tremendous attentions recently. In this network, satellite communications are allowed to operate in the frequency bands allocated to terrestrial networks under the interference constraints imposed by terrestrial network, which may lead to a performance degradation of the satellite network. To guarantee the performance of the primary terrestrial network as well as the secondary satellite network, we introduce the cooperation into cognitive satellite-terrestrial networks and investigate the performance of the new framework, i.e., cognitive satellite-terrestrial cooperative network (CSTCN). Specifically, by restricting the transmit power of satellite communications with interference power constraints imposed by terrestrial communications, we firstly obtain the received signal-to-interference-plus-noise ratio (SINR) of the considered network. Moreover, by employing the moment generating function (MGF) approach, closed-form expressions for symbol error rate (SER) and outage probability (OP) of the considered cognitive network are derived. The analytical results obtained in this paper can provide theoretical support for optimizing the performance of satellite-terrestrial networks.     

Energy efficiency of femtocell deployment in combined wireless/optical access networks

Optical/wireless convergence has become of particular interest recently because a combined radio wireless and optical wired network has the potential to provide both mobility and high bandwidth in an efficient way. Recent developments of new radio access technologies such as the Long Term Evolution (LTE) and introduction of femtocell base stations open new perspectives in providing broadband services and applications to everyone and everywhere, but the instantaneous quality of radio channel varies in time, space and frequency and radio communication is inherently energy inefficient and susceptible to reflections and interference. On the other hand, optical fiber-based networks do not provide mobility, but they are robust, energy efficient, and able to provide both an almost unlimited bandwidth and high availability.In this paper, we analyze the energy efficiency of combined wireless/optical access networks, in which LTE technology provides ubiquitous broadband Internet access, while optical fiber-based technologies serve as wireless backhaul and offer high-bandwidth wired Internet access to business and residential customers. In this contest, we pay a particular attention to femtocell deployment for increasing both access data rates and area coverage. The paper presents a novel model for evaluating the energy efficiency of combined optical/wireless networks that takes into account the main architectural and implementational aspects of both RF wireless and optical parts of the access network. Several hypothetical network deployment scenarios are defined and used to study effects of femtocell deployment and power saving techniques on network’s energy efficiency in urban, suburban and rural areas and for different traffic conditions.     

社区宽带综合业务网服务质量保证的研究

社区宽带综合业务网络系统使用交换式以太网技术,在一个物理网络上为社区用户提供Internet接入、数字电视、IP电话等服务,对三网融合进行了实践性探讨。提出并实现了一套保证系统服务质量的方法,并在测试中取得了满意的效果。     

认知物联网频谱感知数据伪造攻击研究

认知物联网可以看作是＂认知无线电传感器节点的分布式网络＂,它通过在物联网中实现认知无线电技术,可以有效地解决物联网面临的频谱资源紧张等问题。文章提出了认知物联网的基本定义和体系结构,设计了频谱感知数据伪造（SSDF）攻击模型,分析了基于数据融合、基于一致性、基于SVDD算法、基于异常值检测等四种解决方案的原理与性能。     

Can the current generation of wireless mesh networks compete with cellular voice?

Wireless mesh networks are being deployed to provide broadband wireless connectivity to city-wide hotspots. The typical architecture in these deployments thus far is a single-radio architecture: mesh nodes carry only one radio, which is used both to receive the traffic from the clients and to relay this traffic through the mesh to the wired Internet gateway.In this paper, we study the performance of a representative single-radio mesh network both in a live setup and in a laboratory environment. We characterize the performance of different applications (e.g. VoIP), and study some key challenges of mesh networks such as the fairness in bandwidth allocation and hidden node terminal. Finally, we compare the results of the study with traditional cellular networks, and discuss various options to enhance the performance of wireless mesh networks in the future.     

An efficient joint channel assignment and QoS routing protocol for IEEE 802.11 multi-radio multi-channel wireless mesh networks

With the emerging of video, voice over IP (VoIP) and other real-time multimedia services, more and more people pay attention to quality of service (QoS) issues in terms of the bandwidth, delay and jitter, etc. As one effective way of broadband wireless access, it has become imperative for wireless mesh networks (WMNs) to provide QoS guarantee. Existing works mostly modify QoS architecture dedicated for ad hoc or sensor networks, and focus on single radio and single channel case. Meanwhile, they study the QoS routing or MAC protocol from view of isolated layer. In this paper, we propose a novel cross-layer QoS-aware routing protocol on OLSR (CLQ-OLSR) to support real-time multimedia communication by efficiently exploiting multi-radio and multi-channel method. By constructing multi-layer virtual logical mapping over physical topology, we implement two sets of routing mechanisms, physical modified OLSR protocol (M-OLSR) and logical routing, to accommodate network traffic. The proposed CLQ-OLSR is based on a distributed bandwidth estimation scheme, implemented at each node for estimating the available bandwidth on each associated channel. By piggybacking the bandwidth information in HELLO and topology control (TC) messages, each node disseminates information of topology and available bandwidth to other nodes in the whole network in an efficient way. From topology and bandwidth information, the optimized path can be identified. Finally, we conduct extensive simulation to verify the performance of CLQ-OLSR in different scenarios on QualNet platform. The results demonstrate that our proposed CLQ-OLSR outperforms single radio OLSR, multi-radio OLSR and OLSR with differentiated services (DiffServ) in terms of network aggregate throughput, end-to-end packet delivery ratio, delay and delay jitter with reasonable message overheads and hardware costs. In particular, the network aggregate throughput for CLQ-OLSR can almost be improved by 300% compared with the single radio case.     

Mobile broadband internet access service is a commercial mobile service,and hence must be regulated as a common carrier service

ABSTRACT

The FCC’s Restoring Internet Freedom Order reclassified mobile broadband service from a commercial mobile radio service to a private mobile radio service, thereby eliminating common carrier regulation of the service. The reclassification is an incredible assertion: that the most important public mobile service of our time is classified under statute as a private mobile service. We analyze the relevant precedent from the 1940s through 2017. We find that the Order’s lack of consideration of the relevant precedent and technology undermines its interpretation of the statute on which it relies. The Order’s reversion to the 1994 definitions of public switched network and interconnected service ignores the growth of the public switched network to include the Internet. The Order’s conclusion that the public switched telephone network and the Internet are separate non-interconnected networks is factually wrong. Critically, when interpreting interconnection, the Order ignores the fact that in order for meaningful communication to occur, the users’ devices and subscribed services must be compatible. A proper interpretation of relevant statute and precedent leads to the opposite conclusion of the Order, that mobile broadband service is a commercial mobile service. This finding lays the foundation for reinstatement of net neutrality protections on mobile broadband service.     

A tool for the generation of realistic network workload for emerging networking scenarios

Internet workload is a mix of many and complex sources. Therefore, its accurate and realistic replication is a difficult and challenging task. Such difficulties are exacerbated by the multidimensional heterogeneity and scale of the current Internet combined with its constant evolution. The study and generation of network workload is a moving target, both in terms of actors (devices, access networks, protocols, applications, services) and in terms of case studies (the interest expands from performance analysis to topics like network neutrality and security). In order to keep up with the new questions that arise and with the consequent new technical challenges, networking research needs to continuously update its tools. In this paper, we describe the main properties that a network workload generator should have today, and we present a tool for the generation of realistic network workload that can be used for the study of emerging networking scenarios. In particular, we discuss (i) how it tackles the main issues challenging the representative replication of network workload, and (ii) our design choices and its advanced features that make it suitable to analyze complex and emerging network scenarios. To highlight how our tool advances the state-of-the-art, we finally report some experimental results related to the study of hot topics like (a) broadband Internet performance and network neutrality violations; (b) RFC-based security and performance assessment of home network devices; (c) performance analysis of multimedia communications.     

从MOHO实例看国内城域网的现状与应用性前景

MOHO是典型的绿色办公方式,而它的支持环境就是计算机+宽带网络。本文从一般的MOHO(并非特殊行业、特殊应用)实例说明当前国内宽带网络(指小区宽带、固网宽带和无线宽带)的性能、水平。展望不久的将来国内宽带网络与物联网的发展水平。从中看到我国宽带网络的应用性前景。     

Modeling and evaluating IPTV applications in WiMAX networks

Internet Protocol-based Television (IPTV) is a digital television service which delivers television content via an IP network. The rapid growth of wireless network technology in recent years has changed, the way people access the Internet. Adding mobility to IPTV can create a truly compelling ubiquitous service which spans different network domains and varied IP-enabled terminals and devices, such as set-top boxes, PCs and cell phones. However, extending IPTV service to wireless networks requires overcoming bandwidth bottlenecks and high packet loss rates. Following the IEEE 802.16 standard, worldwide interoperability for microwave access (WiMAX) features high data rates and large service coverage, offering a wireless broadband solution for IPTV services. While previous research has focused on creating a broadband IPTV service few studies have practically evaluated IPTV applications in a wireless broadband network environment. In this paper, we model and evaluate a common constant bit rate (CBR)¹ based IPTV application and an IPTV live streaming (PPStreaming)² application while retrieving IPTV content via a WiMAX network. We also use the NS2 simulation tool to evaluate the performance of these two IPTV applications. The evaluation metrics include latency, packet loss, data rate and throughput statistics when the two IPTV applications are run in the WiMAX network. ¹The simplest IPTV solution is to convey video content by CBR. IPTV operators and content delivery networks relay CBR streaming content to control the demand for network capacity. Broadcasters prefer CBR video as it conserves bandwidth resources, but CBR delivery can degrade video quality result in higher overall demand on network capacity. ²PPStreaming (also referred to as P2P streaming Internet TV) is a network for live media streaming. In principle it’s similar to BitTorrent (BT) in that it provides stable and smooth broadcast of TV programs to broadband users. Unlike traditional streaming media, PPStreaming adopts P2P-streaming technology and supports full-scale visits with tens of thousands of simultaneous users. Its client software can be used in the browser or as a standalone executable.     

wmATM enhanced software definable radio system

Driven by the markets and subscribers, broadband telecommunication services are getting more and more significant throughout the world. ATM and Internet technologies are taking the leadership in this storm to bring up the new era of information society. Wireless mobile communication is a very potential system in view of its low cost as well as flexible coverage. Constructing a new broadband, high-speed wireless mobile telecommunications, with full compatibility to existing wireless standards will become an emerging demand in the following years. This kind of system can provide real-time multimedia communications, including voice, data and video to each mobile user or host, and support free roaming and handover any time, anywhere and for anyone. Hence, an intelligent broadband software definable base station is proposed to reflect the advancement of the next generation wireless mobile communications. wmATM (wireless mobile ATM) based software radio will greatly contribute to this technology and enhance the system's performance.     

通过基于ATM方式的ADSL宽带接入技术构建虚拟专用网络

VPN的出现使企业通过Internet既安全又经济地传输私有的机密信息成为可能。而构架在公用网络之上的专用网的性能直接取决于宽带数据接入技术。对基于ATM方式的ADSL宽带接入技术进行了探讨，分析了该种方式开展业务的特点，给出了一种基于ATM方式的ADSL宽带接入技术来构建虚拟专网的实现方案。     

Estimating the performance of intelligent transport systems wireless services for multimodal logistics applications

Various wireless technologies including radio frequency identification (RFID), bluetooth, cellular networks and dedicated short range communications (DSRC) might have an impact on logistics and transport operations. Among them, DSRC stands out as a broadband communications technology which has been designed to provide a general purpose Radio-Frequency (RF) link between vehicles and network infrastructure. As such, DSRC is capable of implementing the physical layer of an Internet Protocol (IP) bearer based network designed to facilitate the monitoring and coordination of portside vehicular traffic. This unprecedented application of wireless networking has the potential to greatly enhance the management of the flow of goods and resources, particularly within large, international ports whose activities comprise multimodal operations such as the use of road haulage to move cargo transported by sea. Given the need for reliable services in non-safety business applications, in this work an Intelligent Transport Systems (ITS) approach is used to address two issues. First, in wireless networks reliable data transfer transport layer services are affected where there is an apparent increase in mobility when access point coverage areas are reduced to counter the effects of path loss in the physical layer. Second, a service provisioning protocol intended for vehicle to infrastructure (V2I) data transfer is proposed to illustrate the importance of cumulative costs in wireless networks used for logistics applications. The analysis covers the average response time for requesting on-demand services within the portside network considered. The results of the analysis confirm the suitability of the approach used to provide a logistics network capable of meeting the requirements demanded in multimodal logistics.     

OmniCon: a Mobile IP‐based vertical handoff system for wireless LAN and GPRS links

Wi‐Fi based hotspots offer mobile users broadband wireless Internet connectivity in public work spaces and corporate/university campuses. Despite the aggressive deployment of these hotspots in recent years, high‐speed wireless Internet access remains restricted to small geographical areas due to the limited physical coverage of wireless LANs. On the other hand, despite their lower throughput, cellular networks have a significantly wider coverage and are thus much more available. Recognizing that 2.5G or 3G cellular networks can effectively complement wireless LANs, we set out to develop a vertical handoff system that allows mobile users to seamlessly fall back to such cellular networks as the general packet radio service (GPRS) or 3G whenever wireless LAN connectivity is not available. The resulting handoff mechanism allows a network connection of a mobile node to operate over multiple wireless access networks in a way that is transparent to end user applications. In this paper, we present the design, implementation, and evaluation of a fully operational vertical handoff system, called OmniCon, which enables mobile nodes to automatically switch between wireless LAN and GPRS, based on wireless LAN availability, by introducing a simple extension to the existing Mobile IP implementation. We discuss the design issues in the proposed vertical handoff system for heterogeneous networks, including connection setup problems due to network address translation, and the disparity in link characteristics between wireless LANs and GPRS. A detailed performance evaluation study of the OmniCon prototype demonstrates its ability to migrate active network connections between these two wireless technologies with low handoff latency and close to zero packet loss. Copyright © 2006 John Wiley & Sons, Ltd.     

An eclectic approach to design tunable amplifiers

Broadband amplifiers that can accommodate commercial communication standards such as GSM, UMTS, Wi‐Fi, and Wi‐Max are extremely important for radio equipment manufacturers. To achieve this coverage, the amplifier should provide high gain and efficiency over a band from 800 to 5200 MHz. Although there are transistor devices that have cut‐off frequencies well over these frequencies, amplifiers covering such a broad‐bandwidth are difficult to design due to the requirement of broadband matching networks. In this work, design of broadband tunable matching networks is investigated using Real Frequency Direct Computational Technique (RF‐DCT). In order to be able to work on sample structures, impedance transforming filters are chosen and a broadband tunable matching network has been designed. Implementation of tunable inductors is investigated and the performance of a tunable matching network using tunable inductors and capacitors is demonstrated. Eventually a broadband frequency tunable amplifier has been designed using the tunable inductor concept. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013.     

WiMAX网络中信噪比与带宽结合的接纳控制算法

呼叫接纳控制（CAC）是宽带无线接入网络无线资源管理中一个重要的组成部分,其中策略设计的好坏直接影响着网络的性能和资源利用率。针对现有基于WiMAX的接纳控制算法仅考虑了带宽作为接纳控制的标准,提出一种结合带宽和信噪比的接纳控制算法,在考虑小区带宽因素的同时能兼顾考虑接纳后业务的信噪比情况。仿真结果表明,结合带宽和信噪比的接纳控制算法可以有效的降低系统中呼叫的掉线率,提高系统性能。     

基于5G切片和优先级的流量隔离性能研究

随着基于3GPP标准的关键任务(MC)移动宽带技术的部署,可为公共保护和救灾提供宽带通信能力。常见方法是在公共移动网络上提供MC服务和商业流量（CO）,并使用优先级机制来保护拥塞情况下的MC连接。然而,这种方法在特定单元中的MC流量激增前,商业流量不受保护,因为所有资源都将被分配来服务于这种流量。在此背景下,提出了一种稳定性较好的多路MC和具有拥塞保护的商业服务的解决方案,该解决方案是基于5G网络切片特性。本文主要描述了在结合优先级的基础上如何在5G无线电接入网(RAN)中参数化不同的切片以及支持无线电资源分配的底层无线电资源管理(RRM)功能的操作从而为每种类型的服务建立无线电负载保证。通过MATLAB仿真结果表明与仅依赖于优先级化机制的解决方案相比,本次采用的切片配置方法在流量隔离方面得到了改进,为不同类型的服务提供了可靠保障。     

Local search methods for efficient router nodes placement in wireless mesh networks

Wireless Mesh Networks (WMNs) are an important networking infrastructure for providing cost-efficient broadband wireless connectivity to a group of users. WMNs are increasingly being used in urban, metropolitan and municipal area networks for deployment of medical, transport, surveillance systems, etc. The performance and operability of WMNs largely depends on placement of mesh routers nodes in the geographical area to achieve network connectivity and stability. The objective is to find an optimal and robust topology of the mesh router network to support intelligent telecommunication services to clients such as adaptive and flexible wireless Internet access, mobile data, voice, video in addition to supporting other preferred client services. In this work, we propose and evaluate local search methods for intelligent placement of mesh routers in WMNs with a two fold objective: maximizing the size of the giant component in the network and user coverage. Given a grid area where to distribute a given number of mesh router nodes, which can have different radio coverage, and a number of fixed clients a priori distributed in the given area, local search methods explore different local movements and incrementally improve the quality of the router nodes placement in terms of network connectivity and user coverage. We have experimentally evaluated the proposed local search methods through a benchmark of generated instances of varying sizes. Moreover, different distributions of mesh clients (Uniform, Normal, Exponential and Weibull) are used. The experimental evaluation showed the good performance of local search methods for optimizing network connectivity and user coverage in WMNs.