低轨星座空口包头去除技术研究

过大的空口IP包头造成了卫星信道带宽资源的严重浪费,为提高带宽利用率,提出了一种低轨卫星移动通信系统中空口IP包头去除技术,通过完全去除IP/UDP/RTP包头来提高数据传输效率。首先分析了该技术在卫星通信系统中应用的可行性,介绍了工作原理,描述了去头、恢复模块的实现流程,搭建了卫星移动通信空口协议栈仿真平台,在空口PDCP协议中增加了包头去除算法,进行了测试和性能分析,并与ROHC压缩算法进行比较。实验测试表明,采用IP包头去除技术将IP/UDP/RTP包头减少为0字节,极大减少了IP数据包头长度,极大提高了IP业务卫星带宽利用率。     

无线网络中提高IP传输效率方法分析

随着无线通信技术的发展,业务种类和数据量急剧增加,使得有限的频带资源变得更加紧张,因此在无线IP网络里,对数据包进行压缩,可以有效提高链路的利用率。这里主要讨论对数据包头进行压缩来提高传输效率。通过分析目前无线网络中IP层传输效率提高的瓶颈,结合目前常用的包头压缩技术,分析了IETF提出的IPHC和ROHC这2种IP头部压缩的方法,并结合无线信道的特点提出适合短生命周期的报文进行头部压缩的机制。     

ROHC协议中CRC计算的硬件实现

ROHC协议是IETF专门针对无线链路的特点而设计的包头压缩规范,CRC码的产生、校验和更新是其中重要的组成部分.在分析CRC快速准确并行算法的基础上,针对ROHC中具体应用要求,给出其CRC计算的硬件并行实现设计方案,并用Verilog HDL语言编写代码进行了仿真和验证,结果表明此方案具有很好的实用性和灵活性.     

包头压缩技术简介

文章阐述了发展包头压缩技术的意义。包头压缩技术及其优势，IETF中的包头压缩技术规范，ROHC标准，3G中有关包头压缩的标准。     

应用于ROHC的CRC算法硬件实现

循环冗余校验(CRC)在很多通信和数据处理领域中得到广泛采用,不同应用领域对其计算需求呈现不规则的情况,无法用统一的方法实现。针对鲁棒包头压缩(ROHC)应用对CRC计算的具体需求(包括数据包序列位数不等、数据长度不规则等),以CRC串行电路结构为基础,得到相应的并行计算公式,设计并优化了CRC生成硬件逻辑结构。该硬件结构简单,不同生成多项式的并行实现电路之间切换调用灵活,数据吞吐量最高可以达到3Gb/s,能够满足无线通信ROHC实时、不规则数据处理的需要。     

一种基于社交网络的卫星IP数据分析算法

针对卫星IP数据分析问题,利用协议分析将非结构化的IP数据文件转化为结构化特征,基于提取的结构化特征构建卫星IP通联网络,并提出了一种基于模块度的IP通联网络自动划分算法,实现了不同网络节点的自动聚类。为进一步提取IP通联网络中的信息,提出了一种基于度和集聚系数的节点重要性评价方法,实现了卫星IP通联网络中节点重要性的自动评价。实验结果表明,提出的算法能够提取卫星IP数据中的有价值信息,可有效支撑卫星通信侦察信息处理。     

IP返回跟踪DoS攻击的压缩边界采样算法

描述了IP返回跟踪DoS(拒绝服务)攻击中的压缩边界采样算法,并在保证后向兼容性的前提下对IP数据包头部进行修改。     

IP返回跟踪DoS(拒绝服务)攻击中的压缩边界采样算法

本文描述了IP返回跟踪DoS(拒绝服务)攻击中的压缩边界采样算法，并在保证后向兼容性的前提下对IP数据包头部进行修改。     

应用于ROHC的窗基LSB编解码修正算法实现机制

在移动：IPv6中，常常因为数据分组的头标太大而消耗过多的带宽，因而需要使用灵活可靠的鲁棒性头标压缩机制(ROHC)来对分组头标进行压缩。在ROHC中，使用LSB编码方案对分组中那些变化比较小的头标域进行编码。本文将在简要介绍ROHC原理的基础上，深入探讨应用于ROHC的窗基LSB编解码修正算法的实现机制。     

可添加规则的创新防火墙设计与实现

个人防火墙一般都是采用包过滤的方式实现的,且大多数的包过滤防火墙只在应用层过滤数据包,不能捕获所有的数据包,安全性较低;而采用内核层的IP过滤钩子驱动则能对所有IP数据包进行过滤,安全性较高。在制定包过滤防火墙的过滤规则前,用户往往需要捕获流经当前主机的数据包进行分析,尽可能地判断出哪些数据包是病毒、木马等非法数据,然后有针对性地制定防火墙规则,才能更有效地阻断恶意数据,保证合法数据的安全。文章正是针对以上两个方面,开发了一个融合抓包和包过滤于一体的防火墙。该防火墙利用内核模式下的IP过滤驱动,来实现防火墙的包过滤功能,提升防火墙的安全性和健壮性。同时调用Winpcap库中的函数,在程序上添加一个抓包模块,为分析数据、制定防火墙规则提供方便。     

Design and Realization of a Novel Header Compression Scheme for Ad Hoc Networks

IP header compression schemes offer a valuable measure for bandwidth preservation. Such schemes have been practically implemented in infrastructure‐based IP networks for point‐to‐point links. However, minimal research and practical implementation efforts have been conducted in the direction of an IP header compression strategy that can meet the peculiar requirements of multi‐hop ad hoc wireless networks. In this paper, we present a practically implemented multi‐hop IP header compression scheme using the Robust Header Compression (ROHC) protocol suite. The scheme runs on a novel identifier (ID) based networking architecture, known as an ID‐based ad hoc network (IDHOCNET). IDHOCNET additionally solves a number of bottlenecks of pure IP‐based ad hoc networks that have emerged owing to IP address auto‐configuration service, distributed naming and name resolution, and the role of an IP address as an identifier at the application layer. The proposed scheme was tested on a multi‐hop test bed. The results show that the implemented scheme has better gain and requires only O (1) ROHC contexts.     

Performance Analysis of a Header Compression Protocol: The ROHC Unidirectional Mode

The performance of IPv6 in the radio link can be improved using header compression algorithms. The 3GPP (3rd Generation Partnership Project) consortium in its technical specification has adopted the ROHC (RObust Header Compression) protocol of the IETF (Internet Engineering Task Force) standard track for real-time applications using RTP/UDP/IPv6 and UDP/IPv6. This paper presents the analysis of the proposed standard ROHC deployed in an UMTS radio link and discusses different schemes to increase compression performance. The results are based on our IPv6 implementation of the ROHC header compression algorithm and on a simple and accurate analytical model used to evaluate the packet loss probability.     

LTE系统中自适应鲁棒性报头压缩算法

LTE系统采用全IP承载,具有比以往无线系统更高的数据速率和更大的系统容量.为了更好地利用系统无线带宽资源,LTE采用了灵活可靠的鲁棒性报头压缩机制(ROHC)来处理过大的无线分组报头.由于无线环境的动态变化,信道质量也会随时发生变化,ROHC压缩算法将变得不大适用.为此,提出了一种自适应的鲁棒性报头压缩算法,根据无线信道的变化情况动态调整ROHC压缩的参数.通过仿真结果表明,相比于ROHC协议的压缩算法,提出的算法具有更好的压缩效率,同时具有更好的适用性.     

WiMAX自适应健壮性报头压缩算法

由于WiMAX通信传输协议框架中各层协议的报头含有太多的冗余信息,导致了无线信道带宽的利用率较低。同时由于分组过长也会引起误码率的增加。为了解决WiMAX中报头开销过大问题,提高无线信道带宽利用率,结合ROHC压缩算法和WiMAX MAC协议,提出了WiMAX自适应健壮性报头压缩方案。通过分析W-LSB编码,给出了自适应健壮性报头压缩算法在WiMAX的实现过程。仿真结果表明：该算法可以将60个字节的RTP/UDP/IPv6报头压缩到1～3个字节;可以适应WiMAX通信系统链路特性经常变化的无线信道,能够在报头压缩率和抗差错鲁棒性之间获得较好的平衡性。     

Demonstration of 100 Gbps optical packet switching using header processor based on 48-bit longest prefix matching

Wire-rate packet processing and its energy saving for over 100 Gbps speed of line are major issues to be resolved in optical packet switching (OPS) networks. For that purpose, we newly develop a high-speed, deterministic-latency electronic header processor based on longest prefix matching (LPM) for searching optical packet destination addresses (OP-DAs). This paper reports the successful experimental results of electronic header processing based on LPM search of up to 48 bits and optical switching of 100 Gbps optical packets by the use of the header processor. We demonstrate 48-bit LPM-capable optical packet switching. We also demonstrate IP packet transfer and 32-bit LPM-capable optical packet switching. In the latter demonstration, the 32-bit OP-DA of optical packets is directly copied from the 32-bit destination address of Internet Protocol version 4 (IPv4) packets. This result indicates that OPS networks can be deployed with electronic IP networks by the use of integrated network operation between OPS and IP networks.     

SDI: a multi-domain SDN mechanism for fine-grained inter-domain routing

Software-defined networking (SDN) scheme decouples network control plane and data plane, which can improve the flexibility of traffic management in networks. OpenFlow is a promising implementation instance of SDN scheme and has been applied to enterprise networks and data center networks in practice. However, it has less effort to spread SDN control scheme over the Internet to conquer the ossification of inter-domain routing. In this paper, we further innovate to the SDN inter-domain routing inspired by the OpenFlow protocol. We apply SDN flow-based routing control to inter-domain routing and propose a fine-granularity inter-domain routing mechanism, named SDI (Software Defined Inter-domain routing). It enables inter-domain routing to support the flexible routing policy by matching multiple fields of IP packet header. We also propose a method to reduce redundant flow entries for inter-domain settings. And, we implement a prototype and deploy it on a multi-domain testbed.     

TMSP: Terminal Mobility Support Protocol

Mobile IP enables IP mobility support for mobile node (MN), but it suffers from triangular routing, packet redirecting, increase in IP header size, and the need for new infrastructure support. This paper details an alternative to enable terminal mobility support for MN. This scheme does not suffer from triangular routing effect and does not require dedicated infrastructure support such as home agent. It also does not increase the size of the IP header and does not require redirection of packets. These benefits are enabled with a tradeoff, which requires modifications on MN and its correspondent node. It uses an innovative IP-to-IP address mapping method to provide IP address transparency for applications and taps on the pervasiveness of SIP as a location service. From our analysis, we show that TMSP is much more efficient than mobile IP in terms of the number of hops as well as overhead. Our prototype implementation also shows that TMSP provides seamless communication for both TCP and UDP connections and the computational overhead for TMSP has minimal impact on packet transmission.     

机载移动通信卫星中继链路的高效传输方法

为了提高机载移动通信卫星中继链路的数据传输效率,给出了一种高效传输方法,先通过转换话音编码方式对语音进行压缩,再把话音数据作为有效负载封装成IP数据包,采用RTP复用和IP/UDP/RTP报头压缩等技术来提高话音数据的传输效率.最后通过仿真说明了这种高效传输方法能提升给机载移动通信的性能.